Autofocus apparatus with correction of focusing data

ABSTRACT

An autofocus apparatus with a photographic optical system having a movably disposed focus adjusting lens, an optical element to split light beams received from an object, a plurality of image forming lenses to form images from portions of the split light beams, a plurality of focusing estimating portions to create focusing data for focusing the image of the object on the corresponding image forming lenses, a data detecting device to detect data for focusing the image, a data creating device to correct the detected focusing data, a selecting portion to select from among the focusing estimating portions, and a moving device to move the focus adjusting lens.

This application is a continuation of U.S. application Ser. No.11/785,764, filed Apr. 19, 2007, and now pending, which is acontinuation application of U.S. application Ser. No. 09/550,640, filedApr. 14, 2000; and now U.S. Pat. No. 7,209,175, which is a divisionalapplication of U.S. application Ser. No. 08/834,926, filed Apr. 7, 1997,now abandoned, and Japanese Application Nos. 8-085192, 8-085193,8-116742, 8-116743, 8-154086, 8-154087, the contents of all of theforegoing being incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an autofocus apparatus and a camerathat are used for a camera, mainly for a video camera and particularlyfor a TV camera. The present invention also relates to a lens barrel anda camera that are used chiefly for a lens interchangeable type videocamera and particularly for a lens interchangeable type TV camera.

2. Related Background Art

There have hitherto been two kinds of autofocus apparatuses as anautofocus apparatus for a camera. One type is generally called a crestclimbing type autofocus apparatus used for mainly a video camera. Theother type is called an image deviation type autofocus apparatusemployed for chiefly a still camera. The two types of autofocusapparatuses will hereinafter be described with reference to thedrawings.

First of all, the crest climbing type autofocus apparatus will beexplained with reference to FIGS. 1 and 2. FIG. 1 is a schematic blockdiagram illustrating the crest climbing type autofocus apparatus. FIG. 2is an explanatory graph showing a relationship between a level of a highfrequency component of a picture signal.

The crest climbing type autofocus apparatus includes, as illustrated inFIG. 1, a photographing optical system 90 constructed of a focusadjusting lens 901, a variable magnification lens 902, a correcting lens903, a stop 904 and an image forming lens 905. This autofocus apparatusalso includes an imaging element 91 for picking up an image formed bythe photographing optical system 90 and converting it into an electricsignal, a picture signal making device 92 for generating a picturesignal corresponding to the electric signal transmitted from the imagingelement 91, and a focusing estimated value creating device 93 forcreating an item of data (a focusing estimated value) for focusing theimage formed on the imaging element 91 on the basis of the picturesignal transmitted from the picture signal making device 92. The crestclimbing type autofocus apparatus further includes a motor 94 for movingthe focus adjusting lens 901 in an optical-axis direction of thephotographing optical system 90, and a motor driving device 95 fordriving the motor 94 referring to the focusing estimated value obtainedby the focusing estimated value creating device 93.

Next, an operation of the crest climbing type autofocus apparatus willbe explained. To begin with, the photographing optical system 90 formsan image on the imaging element 91. This image is, after being convertedinto the electric signal by the imaging element 91, further convertedinto the picture signal by the picture signal making device 92. Thispicture signal can be regarded as being formed by synthesizing sinewaves of a plurality of frequencies.

By the way, it is well known that the level of the high frequencycomponent of the picture signal, as shown in FIG. 2, rises more steeplyas a degree of sharpness of the image formed on the imaging element 91increases, viz., as the focus adjusting lens move closer to a focusingpoint A. Then, it is also a generally known fact that when the image onthe imaging element 91 is focused on, the high frequency component levelof the picture signal reaches its peak. Further, a crest of this levelhas a tendency of becoming steeper with a higher frequency. While on theother hand, an image forming performance of the lens and an S/N ratio ofthe picture signal worsen as the frequency gets higher.

Such being the case, the focusing estimated value creating device 93selects a proper high frequency component from the picture signalobtained by the picture signal making device 92 in consideration of theS/N ratio of the picture signal as well as of the image formingperformance of the photographing optical system 90, and creates afocusing estimated value by monitoring the level of this frequencycomponent at an adequate sampling interval. For example, when the levelof the selected frequency component is rising, it is estimated that thefocus adjusting lens 901 is moving in such a direction as to approach afocusing point. Contrastingly, when the level of the selected frequencycomponent is lowering, it is estimated that the focus adjusting lens 901is moving in such a direction as to get away from the focusing point.Then, when the level of the selected frequency component exists within apredetermined range (shown by e.g., ΔV in FIG. 2), it is estimated thatthe image on the imaging element 91 is focused on.

Next, the motor driving device 95 refers to the focusing estimatedvalues sequentially sent from the focusing estimated value creatingdevice 93, and drives the motor 94 to move the focus adjusting lens 901to such a position as to make a judgement of being focused on. Thus, inthe crest climbing type autofocus apparatus, the focus adjusting lens901 moves as if climbing the crest of the high frequency. This is thereason why the above autofocus apparatus is called the crest climbingtype.

The above crest climbing type autofocus apparatus estimates the focusingby use of the picture signal and is therefore capable of highlyaccurately focusing the image on the imaging element 91 upon thecorresponding object. Further, the image on the imaging element 91 isfocused on without providing an element for an exclusive use ofmeasuring a distance, and hence there must be an advantage costwise.Therefore, the apparatus is used as the autofocus apparatus mainly forthe video camera.

Next, the image deviation type autofocus apparatus will be explainedwith reference to the drawings. FIGS. 3, 5 and 7 are explanatorydiagrams each showing what the principle of the image deviation typeautofocus apparatus is. Herein, FIG. 3 illustrates a light path when ina focused state. FIGS. 5 and 7 show the light paths when in a defocusedstate. Further, throughout the drawings, the numeral 96 designates animage forming optical system for forming the light beams into aconjugate image. The numeral 97 represents a predetermined focal surfaceof the image forming optical system 96, and 98 a, 98 b denote imagere-forming lenses, disposed in positions substantially symmetric withrespect to the optical axis of the image forming optical system 96, forre-forming some of the light beams (image) into images, which beams havebeen image-formed by the image forming optical system 96. Designatedfurther by 99 a, 99 b are line sensors disposed in positionssubstantially symmetric with respect to the optical axis of the imageforming optical system 96 and on predetermined focal surfaces of theimage re-forming lenses 98 a, 98 b.

As illustrated in FIG. 3, when the light beams passing through the imageforming optical system are focused on the predetermined focal surface97, some of the light beams are again image-formed on the line sensors99 a, 99 b through the image re-forming lenses 98 a, 98 b. Accordingly,when focused on the predetermined focal surface 97, images E₁, E₂ pickedup by the two line sensors 99 a, 99 b are, as illustrated in FIG. 4,formed in substantially coincident positions of the line sensors. On theother hand, as shown in FIG. 5, when the light beams passing through theimage forming optical system are focused on anterior to thepredetermined focal surface 97 (which is a so-called rear focus state),there must be a deviation between the images E₁, E₂ picked up by the twoline sensors 99 a, 99 b as shown in FIG. 6. Further, as illustrated inFIG. 7, when the light beams passing through the image forming opticalsystem are focused on posterior to the predetermined focal surface 97(which is a so-called front focus state), there must be, as illustratedin FIG. 8, a deviation between the images picked up by the two linesensors 99 a, 99 b in a direction opposite to that in the rear focusstate.

Hence, it is feasible to calculate a moving direction and a movingquantity of the focus adjusting lens, which are needed for focusing onthe predetermined focal surface 97, by detecting a deviating directionand a deviation quantity between the images picked up by the linesensors 99 a, 99 b. As discussed above, in the image deviation typeautofocus apparatus, the focusing is performed based on the deviatingdirection and the deviation quantity between the images picked up by thetwo line sensors 99 a, 99 b. This is the reason why the above autofocusapparatus is called the image deviation type.

The above-described image deviation type autofocus apparatus directlycalculates the required-for-focusing moving direction and movingquantity of the focus adjusting lens on the basis of the deviatingdirection and the deviation quantity between the images picked up by thetwo line sensors 99 a, 99 b, and is therefore capable of focusingquickly. The image deviation type autofocus apparatus is therefore usedmainly for the still camera.

Principally, the crest climbing type autofocus apparatus has hithertobeen used for the video camera. The video camera to which theconventional crest climbing type autofocus apparatus is applied, willhereinafter be explained with reference to the drawings. FIG. 9 is aschematic block diagram showing the video camera to which the prior artcrest climbing type autofocus apparatus is applied. FIG. 2 is anexplanatory graph showing how a level of a high frequency of the picturesignal relates to a position of the focus adjusting lens.

The video camera to which the conventional crest climbing type autofocusapparatus is applied includes, as illustrated in FIG. 9, a lens barrel 8and a camera body 9 to which the lens barrel 8 is attached.

The lens barrel 8 is so constructed as to be attachable to the camerabody 9, and a user is able to interchange the lens barrel 8 attached tothe camera body 9 according to applications thereof. Further, the lensbarrel 8 has a photographing optical system 120 constructed of a focusadjusting lens 801, a variable magnification lens 802, a correcting lens803, a stop 804 and an image forming lens 805. The lens barrel 8 alsohas a motor 122 for moving the focus adjusting lens 801 in theoptical-axis direction of the photographing optical system 120, and amotor driving circuit 123 for driving the motor 122 based on a motordriving signal transmitted via a connector 125.

The camera body 9 includes an imaging element 91 for picking up theimage obtained by the photographing optical system 120 and converting itinto an electric signal, a picture signal making device 92 forgenerating a picture signal corresponding to the electric signaltransmitted from the imaging element 91, and a focusing estimated valuecreating device 93 for creating the data (a focusing estimated value)for focusing the image on the imaging element 91 on the basis of thepicture signal from the picture signal making device 92. The camera body9 also includes an AF processing circuit 104 for generating a motordriving signal with reference to the focusing estimated value obtainedby the focusing estimated value creating device 93, and a connector 105through which the motor driving signal generated by the AF processingcircuit 104 is transmitted to the motor driving circuit 123 of the lensbarrel 8. Note that the connector 105 is so constructed as to beelectrically connected to a connector 125 of the lens barrel when thelens barrel 8 is attached to the camera body 9.

Next, an autofocusing operation of the video camera shown in FIG. 9 willbe explained. At the first onset, the photographing optical system 120forms the image on the imaging element 91. This image is converted intothe electric signal by the imaging element 91 and thereafter convertedfurther into the picture signal by the picture signal making device 92.This picture signal can be regarded as being formed by synthesizing sinewaves of a plurality of frequencies.

By the way, it is well known that the level of the high frequencycomponent of the picture signal, as shown in FIG. 2, rises more steeplyas a degree of sharpness of the image formed on the imaging element 91increases, viz., as the focus adjusting lens move closer to a focusingpoint A. Then, it is also a generally known fact that when the image onthe imaging element 91 is focused on, the high frequency component levelof the picture signal reaches its peak. Further, a crest of this levelhas a tendency of becoming steeper with a higher frequency. While on theother hand, an image forming performance of the lens and an S/N ratio ofthe picture signal worsen as the frequency gets higher.

Such being the case, the focusing estimated value creating device 93selects a proper high frequency component from the picture signalobtained by the picture signal making device 92 in consideration of theS/N ratio of the picture signal as well as of the image formingperformance of the photographing optical system 120, and creates afocusing estimated value by monitoring the level of this frequencycomponent at an adequate sampling interval. For example, when the levelof the selected frequency component is rising, it is estimated that thefocus adjusting lens 801 is moving in such a direction as to approach afocusing point. Contrastingly, when the level of the selected frequencycomponent is lowering, it is estimated that the focus adjusting lens 801is moving in such a direction as to get away from the focusing point.Then, when the level of the selected frequency component exists within apredetermined range (shown by e.g., ΔV in FIG. 2), it is estimated thatthe image on the imaging element 91 is focused on.

Next, the AF processing circuit 104 refers to the focusing estimatedvalues sequentially sent from the focusing estimated value creatingdevice 93, and generates a motor driving signal to move the focusadjusting lens 801 to such a position as to make a judgement of beingfocused on. The motor driving circuit 123 drives the motor 122 based onthe motor driving signal generated by the AF processing circuit 104.

Thus, in the crest climbing type autofocus apparatus, the focusadjusting lens 801 moves as if climbing the crest of the high frequency.This is the reason why the above autofocus apparatus is called the crestclimbing type.

The video camera to which the above crest climbing type autofocusapparatus is applied, estimates the focusing by use of the picturesignal and is therefore capable of well accurately focusing on theobject corresponding to the image on the imaging element 91. Further,this video camera is advantageous costwise because of focusing the imageon the imaging element 91 without providing an element for an exclusiveuse of measuring a distance.

In the above-described crest climbing type autofocus apparatus, thefocus adjusting lens 901 is moved to such a position as to make thejudgement of being focused while referring to the focusing estimatedvalues sequentially transmitted from the focusing estimated valuecreating device 93 at a predetermined sampling interval. This might leadto a problem, in which it takes much time to attain the focusing.Especially when the focus adjusting lens 901 is positioned far from thefocusing point (which is a so-called largely defocused state), asillustrated in FIG. 2, a variation in the high frequency component levelof the picture signal might be small enough to be hidden by noises,etc., or there must be a high possibility of not indicating a peak ofthe level thereof. Consequently, the focusing estimated value creatingdevice 93 becomes harder to make the estimation. Therefore, the timetill the focusing is attained might extremely elongate in some cases.

The problem of requiring a good deal of time for focusing might bringabout a possibility in which the photographer would miss aninstantaneous photographing chance on the occasion of reporting news andso forth when, e.g., the above crest climbing type autofocus apparatusis used for the TV camera.

In this respect, the above image deviation type autofocus apparatus is,as stated earlier, capable of focusing quickly. When the image deviationtype autofocus apparatus is employed for the video camera, however, itis required that the light beams be diverged from the photographingoptical system for forming the image on the imaging element, and theimage be formed in a position different from the imaging elementsurface. Therefore, whether or not the image on the imaging element befocused on is estimated by making use of the image formed in theposition different from the imaging element surface. Hence, this leadsto a problem of being incapable of focusing with a high accuracy. Thehigh accuracy (a deviation on the image surface in the optical-axisdirection of the photographing optical system is within approximatelyseveral μm), is required of particularly the autofocus apparatus for theTV camera. Meeting this accuracy in the above image deviation typeautofocus apparatus must involve a remarkable increase in costs.

Further, in the video camera to which the above prior art crest climbingtype autofocus apparatus is applied, the focus adjusting lens 801 ismoved to such a position as to make the judgement of being focused whilereferring to the focusing estimated values sequentially transmitted fromthe focusing estimated value creating device 93 at the predeterminedsampling interval. Therefore, the problem is that the focusing mightneed much time. In particular, when the focus adjusting lens 801 ispositioned far from the focusing point (which is the so-called largelydefocused state), as shown in FIG. 2, the level of the high frequencycomponent of the picture signal remains almost unchanged even by movingthe focus adjusting lens 801. Hence, the focusing estimated valuecreating device 93 is hard to make the estimation in terms ofconsidering the noises, etc. contained in the high frequency components.Consequently, the time needed till the focusing is attained mightextremely elongate in some cases. The problem of requiring a good dealof time till the focusing is done might further conduce to thepossibility, wherein the photographer would miss the instantaneousphotographing chance on the occasion of reporting news when, e.g., theabove-described crest climbing type autofocus apparatus is used for theTV camera.

Moreover, in the video camera to which the above prior art crestclimbing type autofocus apparatus is applied, as illustrated in FIG. 9,the camera body incorporates the focusing estimated value creatingdevice and the AF processing device. Therefore, in the video camera,both of the camera body corresponding the autofocusing and the lensbarrel corresponding to the relevant camera body, are needed foractualizing the autofocus function. Particularly the camera body of theTV camera employed by a professional cameraman is, however, veryexpensive and therefore causes such a problem that the user is forced toexpend much in order to actualize the autofocus function in that TVcamera.

Furthermore, when replacing the lens barrel attached to the video camerabody, a so-called tracking adjustment is required to be performed,wherein a predetermined focal surface of the lens barrel is adjusted tothe imaging element surface of the video camera body by moving the imageforming lens of the lens barrel in the optical-axis direction of thelens barrel. Upon carrying out the tracking adjustment, there must beproduced a deviation in an optical positional relationship between theimaging element surface of the video camera body and the predeterminedfocal surface 97 for estimating the focusing, resulting in a decline interms of the focusing accuracy.

SUMMARY OF THE INVENTION

It is a primary object of the present invention, which was contrivedunder such circumstances, to provide an autofocus apparatus, a cameraand a lens barrel that are inexpensive and capable of focusing quicklywith a high accuracy.

It is another object of the present invention to provide a lens barrelcapable of actualizing an autofocus function even when attached to acamera body incorporating no autofocus function.

It is a further object of the present invention to provide an autofocusapparatus capable of focusing on a photographing target at a highefficiency.

To accomplish the above objects, an autofocus apparatus according to thepresent invention comprises a photographing optical system having atleast a focus adjusting lens disposed movably and an optical element forsplitting light beams inputted and emerging from an object. Theautofocus apparatus also comprises a first focusing estimating devicehaving a first optical system for forming an image corresponding to theobject by inputting one light beam of the light beams split by theoptical element, a first imaging element for picking up the imageobtained by the first optical system and converting it into an electricsignal, and a first data creating device for selecting a properfrequency component from the electric signal obtained by the firstimaging element and, on the basis of a level of this frequencycomponent, creating an item of data for focusing the image on the firstimaging element upon the object. The autofocus apparatus furthercomprises a second focusing estimating device having a second opticalsystem for forming an image corresponding to the object by inputting theother light beam of the light beams split by the optical system, animage re-forming optical system for respectively re-forming, intoimages, the light beams passing through portions with different pupilsamong the light beams for forming the image formed by the second opticalsystem, a second imaging element for picking up the images obtained bythe image re-forming optical system, and a second data creating devicefor creating an item of data for focusing the image on the first imagingelement upon the object on the basis of a positional deviation betweenthe images on the second imaging element. The autofocus apparatus stillfurther comprises a focusing estimation selecting device for selectingat least one item of data out of the data given from the first focusingestimating device and the data from the second focusing estimatingdevice, and a moving device for moving the focus adjusting lens on thebasis of the data selected by the focusing estimation selecting device.

Herein, it is preferable that the focusing estimation selecting deviceselects the data from the second focusing estimating device when theimage picked up by the first imaging element is roughly focused on, andselects the data from the first focusing estimating device when theimage picked up by the first imaging element is finely focused on.

Further, the focusing estimation selecting device, if any one item ofthe data of two items of data from the first focusing estimating deviceand from the second focusing estimating device is useless, may selectthe other item of data. Herein, “being useless” implies a case in whichthe image on the first imaging element can not be focused with thatestimated value. It is because, as described in the prior art, theprinciple of the crest climbing method is absolutely different from thatof the image deviation method, and the focusing point is undetectabledepending on the objects as the case may be.

Furthermore, the focusing estimation selecting device may select any oneitem of data of two items of data from the first focusing estimatingdevice and from the second focusing estimating device with reference todata for specifying a depth of field. Herein, the “data for specifyingthe depth of field” correspond to, e.g., an aperture value of thephotographing optical system, positions of the focus adjusting lens andof the variable magnification lens in the photographing optical system,and an existence or non-existence and a kind of an optical accessary.

The autofocus apparatus according to the present invention may furthercomprise an object dimension calculating device for calculating a realdimension of the object on the basis of a distance from an image sideprincipal point of the photographing optical system to an image surface,a distance from an object-side principal point of the photographingoptical system to the object, and a dimension of the object on the firstimaging element. The autofocus apparatus may still further comprise anobject dimension setting device for setting a dimension of the object,and a focusing object controlling device for comparing the object realdimension calculated by the object dimension calculating device with theobject dimension set by the object dimension setting device, andcontrolling the first focusing estimating device and the second focusingestimating device on the basis of a result of this comparison.

The real dimension Y of the object is expressed by the followingformula:Y=ay/bwhere b is the distance from the image side principal point of thephotographing optical system to the image surface, a is the distancefrom the object-side principal point of the photographing optical systemto the object, and y is the dimension of the object on the first imagingelement. Herein, the distance a from the object-side principal point ofthe photographing optical system to the object, can be calculated basedon an imaging positional deviation between the images respectivelypicked up by the plurality of second imaging elements in the secondfocusing estimating device. Further, the dimension y of the object onthe first imaging element can be obtained by executing the imageprocessing on the electric signal transmitted from the first imagingelement.

Incidentally, it is preferable that the focusing object controllingdevice controls the first focusing estimating device and the secondfocusing estimating device so as to focus on the relevant object whenthe object real dimension calculated by the object dimension calculatingdevice is substantially the same as the object dimension set by theobject dimension setting device, or alternatively the focusing objectcontrolling device controls the first focusing estimating device and thesecond focusing estimating device so as to focus on an object exclusiveof the relevant object.

Moreover, if the second focusing estimating device is disposed so thatthe plurality of image re-forming optical systems and the plurality ofsecond imaging elements are capable of picking up a plurality ofportions of the image formed by the second optical system, it ispreferable that the object dimension calculating device is capable ofcalculating the real dimension of respective objects corresponding tothe plurality of portions of the image formed by the second opticalsystem.

Furthermore, it is preferable that the object real dimension calculatedby the object dimension calculating device is displayed on a displaymedium such as a monitor, a finder, etc. or stored on storage mediumsuch as a video tape or the like together with the picture signal.

The autofocus apparatus according to the present invention may furthercomprise a focus area setting device for setting a size of a focus area.The first focusing judging device may create the data for focusing theimage on the first imaging element upon the object, with respect to thefocus area having the size set by the focus area setting device. Herein,the “focus area” is an area in which to create the data for focusing onthe object in an area on the first imaging element.

Note that the focus area setting device preferably sets the size of thefocus area of the first focusing estimating device smaller than thefocus area of the second focusing estimating device. Further, the focusarea setting device may set the size of the focus area of the firstfocusing estimating device larger than the focus area of the secondfocusing estimating device.

Moreover, when a plurality of focus areas are previously set in thesecond focusing estimating device, it is preferable that the focus areasetting device detects the focus areas adjacent to each other and havingsubstantially the same distance from the photographing optical system tothe object corresponding to the image on the relevant focus area out ofthe plurality of focus areas on the basis of pieces of data respectivelycreated about the plurality of focus areas by the second focusingestimating device, and sets a size of the focus area of the firstfocusing estimating device in accordance with a total size of thesefocus areas.

Also, a focus size inputting device for inputting data about the size ofthe focus area is provided, and the focus area setting device may setthe size of the focus of the first focusing estimating device on thebasis of the data about the focus area size inputted by the focus sizeinputting device.

The autofocus apparatus according to the present invention may beprovided with a focus position inputting device for inputting data abouta position of the focus area. The first focusing judging device and thesecond focusing judging device may create the data for focusing theimage on the first imaging element upon the object with respect to thefocus area existing in the position inputted by the focus positioninputting device.

Note that the focusing estimation selecting device preferably selectsonly the data given from the first focusing estimating device when thefocus area position inputted by the focus position inputting device is aposition in which the image can not be detected by the image re-formingoptical system of the second focusing estimating device.

Displayed also on a display medium such as a monitor, a finder, etc. arethe data by which the focus area of the first focusing estimating devicecan be identified when the focusing estimation selecting device selectsthe data obtained by the first focusing estimating device, and the databy which the focus area of the second focusing estimating device can beidentified when selecting the data obtained by the second focusingestimating device.

Another autofocus apparatus according to the present invention comprisesa photographing optical system having at least a focus adjusting lensdisposed movably, and an image forming lens for forming an imagecorresponding to an object by inputting light beams emerging from theobject. The autofocus apparatus also comprises an imaging element forpicking up an image obtained by the photographing optical system andconverting it into an electric signal, and a data creating device forselecting a proper frequency component from the electric signal obtainedby the imaging element, and creating an item of data for focusing theimage on the imaging element upon the object on the basis of a level ofthis frequency component. The autofocus apparatus further comprises amoving device for moving the focus adjusting lens on the basis of thedata created by the data creating device. The autofocus apparatus mayalso comprise a distance measuring device for measuring a distance froman object-side principal point of the photographing optical system tothe object. The autofocus apparatus may further comprise an objectdimension calculating device for calculating a real dimension of theobject on the basis of the distance, measured by the distance measuringdevice, from an object-side principal point of the photographing opticalsystem to the object, a distance from an image side principal point ofthe photographing optical system to an image surface, and a dimension ofthe object on the first imaging element, an object dimension settingdevice for setting a dimension of the object, and a focusing objectcontrolling device for comparing the object real dimension calculated bythe object dimension calculating device with the object dimension set bythe object dimension setting device, and controlling an area in whichthe data creating device creates the data for focusing the image on thefirst imaging element upon the object on the basis of a result of thiscomparison.

Still another autofocus apparatus according to the present inventioncomprises a photographing optical system having at least a focusadjusting lens disposed movably, and an optical element for splittinglight beams inputted and emerging from an object, and a first opticalsystem for forming an image corresponding to the object by inputting onelight beam of the light beams split by the optical element. Theautofocus apparatus also comprises a first imaging element for pickingup the image obtained by the first optical system, a second opticalsystem for forming the image corresponding to the object by inputtingthe other light beam of the light beams split by the optical element,and an image re-forming optical system for respectively re-forming, intoimages, the light beams passing through portions with different pupilsamong the light beams for forming the image formed by the second opticalsystem. The autofocus apparatus further comprises a second imagingelement for picking up the images obtained by the image re-formingoptical system, a data creating device for creating an item of data forfocusing the image on the first imaging element upon the object on thebasis of a positional deviation between the images on the second imagingelement, a moving device for moving the focus adjusting lens on thebasis of the data created by the data creating device, and an objectdimension calculating device for calculating a real dimension of theobject on the basis of a distance from an image side principal point ofthe photographing optical system to an image surface, a distance from anobject-side principal point of the photographing optical system to theobject, and a dimension of the object on the first imaging element. Theautofocus apparatus still further comprises an object dimension settingdevice for setting a dimension of the object, and a focusing objectcontrolling device for comparing the object real dimension calculated bythe object dimension calculating device with the object dimension set bythe object dimension setting device, and controlling an area in whichthe data creating device creates the data for focusing the image on thefirst imaging element upon the object on the basis of a result of thiscomparison.

A camera according to the present invention is attachable with a lensbarrel comprising a photographing optical system having at least a focusadjusting lens disposed movably, and an optical element for splittinglight beams inputted and emerging from an object, a first optical systemfor forming an image corresponding to the object by inputting one lightbeam of the light beams split by the optical element, and a movingdevice for moving the focus adjusting lens. Preferably, the cameracomprises a first focusing estimating device having a first imagingelement for picking up the image obtained by the first optical systemand converting it into an electric signal, and a first data creatingdevice for selecting a proper frequency component from the electricsignal obtained by the first imaging element and, on the basis of alevel of this frequency component, creating an item of data for focusingthe image on the first imaging element upon the object. The camera alsocomprises a second focusing estimating device having a second opticalsystem for forming an image corresponding to the object by inputting theother light beam of the light beams split by the optical system, animage re-forming optical system for respectively re-forming, intoimages, the light beams passing through portions with different pupilsamong the light beams for forming the image formed by the second opticalsystem, a second imaging element for picking up the images obtained bythe image re-forming optical system, and a second data creating devicefor creating an item of data for focusing the image on the first imagingelement upon the object on the basis of a positional deviation betweenthe images on the second imaging element. The camera further comprises afocusing estimation selecting device for selecting at least one item ofdata out of the data given from the first focusing estimating device andthe data from the second focusing estimating device, and a controllingdevice of controlling the moving device on the basis of the dataselected by the focusing estimation selecting device.

Herein, the first focusing estimating device estimates the image on thefirst imaging element by use of a so-called crest climbing method. Asstated in the prior art, it is well known that the level of the highfrequency component of the electric signal obtained by the imagingelement rises more steeply according as a degree of sharpness of theimage formed on the imaging element increases, videlicet, as the focusadjusting lens moves closer to the focusing point, and this levelreaches its peak when the image on the imaging element is focused on.This being the case, the first focusing estimating device selects aproper frequency component in consideration of an S/N ratio of theelectric signal as well as of an imaging performance of thephotographing optical system, out of the electric signal obtained by thefirst imaging element. Then, the first focusing estimating devicecreates the data (a focusing estimated value) for focusing the image onthe first imaging element by monitoring the level of this frequencycomponent at a predetermined sampling interval. For example, when thelevel of the selected frequency component rises, it is estimated thatthe focus adjusting lens is moving in such a direction as to approachthe focusing point. Further, when the level of the selected frequencycomponent lowers, it is estimated that the focus adjusting lens ismoving in such a direction as to get away from the focusing point. Then,when the level of the selected frequency component exists within apredetermined range from the peak value, it is estimated that the imageon the first imaging element is focused on.

Moreover, the second focusing estimating device estimates the image onthe first imaging element by use of a so-called image deviation method.The light beams diverged by the photographing optical system, afterbeing image formed by the second optical system, pass through theplurality of image re-forming optical systems and respectively formimages on the corresponding second imaging elements. Herein, it ispreferable that each of the second imaging elements is disposed to makeoutput signals of the picked-up images coincident with each other whenthe image on the first imaging element is focused on. The second datacreating device detects a deviating direction and a deviation quantitybetween the images picked up by the respective imaging elements, therebycreating the data (the focusing estimated value) for focusing the imageon the first imaging element.

In the autofocus apparatus of the present invention, the first focusingestimating device creates the focusing estimated value by use of theso-called crest climbing method, and the second focusing estimatingdevice creates the focusing estimated value by use of the so-calledimage deviation method. Then, the focusing estimation selecting deviceselects at least one of the focusing estimated value created by thefirst focusing estimating device and the focusing estimated valuecreated by the second focusing estimating device, and the focusadjusting lens is moved based on the selected focusing estimated value.

Accordingly, the focusing estimation selecting device is set so that atfirst the image on the first imaging element is roughly focused on byuse of the focusing estimated value of the second focusing estimatingdevice, and thereafter the image on the first imaging element is finelyfocused on by employing the focusing estimated value of the firstfocusing estimating device. It is therefore feasible to execute focusingquickly with a high accuracy. Further, the high accuracy is not requiredof the second focusing estimating device using the image deviationmethod, and hence the costs can be restrained.

Further, if any one of the first focusing estimated value and the secondfocusing estimated value is useless, the focusing estimation selectingdevice is set to select the other estimated value, whereby the focusingon the object can be done more surely.

Furthermore, the focusing estimation selecting device is set to selectat least one of the first focusing estimated value and the secondfocusing estimated value with reference to the depth of field. With thissetting, it is possible to select the data given from the secondfocusing estimating device if a focusing accuracy in the first focusingestimating device is inferior to a focusing accuracy in the secondfocusing estimating device.

Moreover, the autofocusing apparatus of the present invention isprovided with the object dimension calculating device, the objectdimension setting device and the focusing object controlling device thatare constructed as described above. With this construction, a focusingrange can be further limited by focusing on the object concerned onlywhen the object real dimension calculated by the object dimensioncalculating device is coincident with a photographing target dimensionset by the object dimension setting device. Further, the first focusingestimating device is made to create the estimated value in a small area,with the result that the second focusing estimating device does notnecessarily create the estimated value in the small area enough todecrease a resolution of the second focusing estimating device. Thecosts for the second focusing estimating device can be therebyrestrained.

Moreover, when the autofocus apparatus of the present invention isprovided with the above-constructed focus area setting device, forexample, the focus area of the first focusing estimating device is setsmaller than the focus area of the second focusing estimating device,thereby making it feasible to decrease a detection sensitivity of theimaging positional deviation with respect to the second focusingestimating device. The resolution of the second imaging element can bethereby enhanced, and consequently the costs for the second focusingestimating device can be restrained.

Further, in another autofocus apparatus according to the presentinvention, with the construction described above, for instance, only aspecified object (e.g., human being) can be focused on from within thephotographic area by focusing on the object concerned only when theobject real dimension calculated by the object dimension calculatingdevice is coincident with the photographing target dimension set by theobject dimension setting device.

A lens barrel according to the present invention is attachable to acamera body having a first focusing estimating device for creatingfocusing data for focusing an image on an imaging surface upon an objecton the basis of a level of a frequency component selected from anelectric signal obtained by an image formed on the imaging surface.Preferably, the lens barrel comprises a photographing optical systemhaving a focus adjusting lens disposed movably, a beam splitting elementfor splitting light beams incident on the focus adjusting lens andemerging from the object, and a first image forming lens for forming onelight beam of the light beams split by the beam splitting element intoan image. The photographing optical system guides the light beamincident on the first image forming lens and emerging from the objectonto the imaging surface. The lens barrel also comprises a secondfocusing estimating device having a second image forming lens forforming the other light beam of the light beams split by the beamsplitting element into an image, at least one pair of image re-forminglenses for respectively re-forming, into images, the light beamsemerging from the object which beams have been image-formed by thesecond image forming lens, and an imaging element for picking up theimages obtained by at least one pair of image re-forming lenses, thesecond focusing estimating device creating an item of focusing data forfocusing the image on the imaging surface upon the object on the basisof an imaging positional deviation on the imaging element between theimages obtained by at least one pair of image re-forming lenses. Thelens barrel further comprises a moving device for moving the focusadjusting lens on the basis of the focusing data created by the firstfocusing estimating device or the second focusing estimating device.

It is preferable that the lens barrel according to the present inventionfurther comprises a selecting device for selecting at least one of thefirst focusing estimating device and the second focusing estimatingdevice. The moving device moves the focus adjusting lens on the basis ofthe focusing data created by the focusing estimating device selected bythe selecting device.

A lens barrel according to the present invention is attachable to acamera body for generating an electric signal based on an image formedin an imaging surface. Preferably, the lens barrel comprises aphotographing optical system having a focus adjusting lens disposedmovably, a beam splitting element for splitting light beams incident onthe focus adjusting lens and emerging from an object, and a first imageforming lens for forming one light beam of the light beams split by thebeam splitting element into an image. The photographing optical systemguides the light beam incident on the first image forming lens andemerging from the object onto the imaging surface. The lens barrel alsocomprises a first focusing estimating device for creating focusing datafor focusing an image on the imaging surface upon the object on thebasis of a level of a frequency component selected from the electricsignal. The lens barrel further comprises a second focusing estimatingdevice having a second image forming lens for forming the other lightbeam of the light beams split by the beam splitting element into animage, at least one pair of image re-forming lenses for respectivelyre-forming, into images, the light beams emerging from the object whichbeams have been image-formed by the second image forming lens, and animaging element for picking up the images obtained by at least one pairof image re-forming lenses, the second focusing estimating devicecreating an item of focusing data for focusing the image on the imagingsurface upon the object on the basis of an imaging positional deviationon the imaging element between the images obtained by at least one pairof image re-forming lenses. The lens barrel still further comprises aselecting device for selecting at least one of the first focusingestimating device and the second focusing estimating device, and amoving device for moving the focus adjusting lens on the basis of thefocusing data created by the focusing estimating device selected by theselecting device.

In the present invention, it is preferable that the selecting device, ifthe imaging positional deviation detected by the positional deviationdetecting device is under a predetermined value, selects the firstfocusing estimating device and, if larger than the predetermined value,selects the second focusing estimating device.

A lens barrel according to the present invention is attachable to acamera body containing identification data indicating whether to have afirst focusing estimating device for creating an item of focusing datafor focusing an image on an imaging surface upon an object on the basisof a level of a predetermined frequency component selected from anelectric signal obtained by an image formed on the imaging surface.Preferably, the lens barrel comprises a photographing optical systemhaving a focus adjusting lens disposed movably, a beam splitting elementfor splitting light beams incident on the focus adjusting lens andemerging from an object, and a first image forming lens for forming onelight beam of the light beams split by the beam splitting element intoan image. The photographing optical system guides the light beamincident on the first image forming lens and emerging from the objectonto the imaging surface. The lens barrel also comprises a secondfocusing estimating device having a second image forming lens forforming the other light beam of the light beams split by the beamsplitting element into an image, at least one pair of image re-forminglenses for respectively re-forming, into images, the light beamsemerging from the object which beams have been image-formed by thesecond image forming lens, and an imaging element for picking up theimages obtained by at least one pair of image re-forming lenses, thesecond focusing estimating device creating an item of focusing data forfocusing the image on the imaging surface upon the object on the basisof an imaging positional deviation on the imaging element between theimages obtained by at least one pair of image re-forming lenses. Thelens barrel further comprises a judging device for judging whether ornot the camera body has the first focusing estimating device on thebasis of the identification data, and a selecting device for selecting,if the judging device judges that the camera body does not have thefirst focusing estimating device, the second focusing estimating device,and selecting, if the judging device judges that the camera body has thefirst focusing estimating device, at least one of the first focusingestimating device and the second focusing estimating device. The lensbarrel still further comprises a moving device for moving the focusadjusting lens on the basis of the focusing data created by the focusingestimating device selected by the selecting device.

In the present invention, it is preferable that the selecting device,when the judging device judges that the camera body has the firstfocusing estimating device, selects the first focusing estimating deviceif the imaging positional deviation detected by the positional deviationdetecting device is under a predetermined value, and, if larger than thepredetermined value, selects the second focusing estimating device.

A camera according to the present invention preferably comprises acamera body for generating an electric signal based on an image form onan imaging surface, and a lens barrel comprising a photographing opticalsystem having a focus adjusting lens disposed movably, a beam splittingelement for splitting light beams incident on the focus adjusting lensand emerging from an object, and a first image forming lens for formingone light beam of the light beams split by the beam splitting elementinto an image. The photographing optical system guides the light beamincident on the first image forming lens and emerging from the objectonto the imaging surface. The camera also comprises a first focusingestimating device for creating focusing data for focusing an image onthe imaging surface upon the object on the basis of a level of afrequency component selected from the electric signal, and a secondfocusing estimating device having a second image forming lens forforming the other light beam of the light beams split by the beamsplitting element into an image, at least one pair of image re-forminglenses for respectively re-forming, into images, the light beamsemerging from the object which beams have been image-formed by thesecond image forming lens, and an imaging element for picking up theimages obtained by at least one pair of image re-forming lenses, thesecond focusing estimating device creating an item of focusing data forfocusing the image on the imaging surface upon the object on the basisof an imaging positional deviation on the imaging element between theimages obtained by at least one pair of image re-forming lenses. Thecamera further comprises a selecting device for selecting at least oneof the first focusing estimating device and the second focusingestimating device, and a moving device for moving the focus adjustinglens on the basis of the focusing data created by the focusingestimating device selected by the selecting device. The camera bodyincorporates the first focusing estimating device and the selectingdevice, while the lens barrel incorporates the second focusingestimating device and the moving device.

A camera according to the present invention preferably comprises acamera body for generating an electric signal based on an image form onan imaging surface, and a lens barrel comprising a photographing opticalsystem having a focus adjusting lens disposed movably, a beam splittingelement for splitting light beams incident on the focus adjusting lensand emerging from an object, and a first image forming lens for formingone light beam of the light beams split by the beam splitting elementinto an image. The photographing optical system guides the light beamincident on the first image forming lens and emerging from the objectonto the imaging surface. The camera also comprises a first focusingestimating device for creating focusing data for focusing an image onthe imaging surface upon the object on the basis of a level of afrequency component selected from the electric signal, and a secondfocusing estimating device having a second image forming lens forforming the other light beam of the light beams split by the beamsplitting element into an image, at least one pair of image re-forminglenses for respectively re-forming, into images, the light beamsemerging from the object which beams have been image-formed by thesecond image forming lens, and an imaging element for picking up theimages obtained by at least one pair of image re-forming lenses, thesecond focusing estimating device creating an item of focusing data forfocusing the image on the imaging surface upon the object on the basisof an imaging positional deviation on the imaging element between theimages obtained by at least one pair of image re-forming lenses. Thecamera further comprises a selecting device for selecting at least oneof the first focusing estimating device and the second focusingestimating device, and a moving device for moving the focus adjustinglens on the basis of the focusing data created by the focusingestimating device selected by the selecting device. The camera bodyincorporates the first focusing estimating device, while the lens barrelincorporates the second focusing estimating device, the selecting deviceand the moving device.

A camera according to the present invention preferably comprises acamera body for picking up an image formed on a predetermined plane, anda lens barrel comprising a photographing optical system, having a focusadjusting lens disposed movably, for guiding the light beam incident onthe focus adjusting lens and emerging from an object onto thepredetermined plane. The camera body contains identification dataindicating whether or not the camera body has a first focusingestimating device for creating focusing data for focusing the image onthe predetermined plane upon the object. The lens barrel furthercomprises a second focusing estimating device for creating the focusingdata for focusing the image on the predetermined plane upon the object,a judging device for judging whether or not the camera body has thefirst focusing estimating device on the basis of the identificationdata, a selecting device for selecting the second focusing estimatingdevice when the judging device judges that the camera body does not havethe first focusing estimating device, and selecting at least one of thefirst focusing estimating device and the second focusing estimatingdevice when the judging device judges that the camera body has the firstfocusing estimating device, and a moving device for moving the focusadjusting lens on the basis of the focusing data created by the focusingestimating device selected by the selecting device.

A camera according to the present invention preferably comprises acamera body for generating an electric signal based on an image formedon an imaging surface, and a lens barrel comprising a photographingoptical system having a focus adjusting lens disposed movably, a beamsplitting element for splitting light beams incident on the focusadjusting lens and emerging from an object, and a first image forminglens for forming one light beam of the light beams split by the beamsplitting element into an image. The photographing optical system guidesthe light beam incident on the first image forming lens and emergingfrom the object onto the imaging surface. The camera body containsidentification data indicating whether or not the camera body has afirst focusing estimating device for creating focusing data for focusingthe image on the imaging surface upon the object on the basis of a levelof a predetermined frequency component selected from the electricsignal. The lens barrel further comprises a second focusing estimatingdevice having a second image forming lens for forming the other lightbeam of the light beams split by the beam splitting element into animage, at least one pair of image re-forming lenses for respectivelyre-forming, into images, the light beams emerging from the object whichbeams have been image-formed by the second image forming lens, and animaging element for picking up the images obtained by at least one pairof image re-forming lenses, the second focusing estimating devicecreating an item of focusing data for focusing the image on the imagingsurface upon the object on the basis of the imaging positional deviationon the imaging element between the images obtained by at least one pairof image re-forming lenses. The lens barrel further comprises a judgingdevice for judging whether or not the camera body has the first focusingestimating device on the basis of the identification data, and aselecting device for selecting the second focusing estimating devicewhen the judging device judges that the camera body does not have thefirst focusing estimating device, and selecting at least one of thefirst focusing estimating device and the second focusing estimatingdevice when the judging device judges that the camera body has the firstfocusing estimating device. The lens barrel further comprises a movingdevice for moving the focus adjusting lens on the basis of the focusingdata created by the focusing estimating device selected by the selectingdevice.

A lens barrel according to the present invention is attachable to acamera body for generating an electric signal based on an image formedon an imaging surface. Preferably, the lens barrel comprises aphotographing optical system having a focus adjusting lens disposedmovably, and an image forming lens for forming a light beam incident onthe focus adjusting lens and emerging from an object into an image. Thephotographing optical system guides the light beam incident on the imageforming lens and emerging from the object onto the imaging surface. Thelens barrel also comprises a focusing estimating device for creating anitem of focusing data for focusing the image on the imaging surface uponthe object on the basis of a level of a predetermined frequencycomponent selected from the electric signal, and a moving device formoving the focus adjusting lens on the basis of the focusing datacreated by the focusing estimating device.

A lens barrel according to the present invention is attachable to acamera body for picking up an image formed on a predetermined plane.Preferably, the lens barrel comprises a photographing optical systemhaving a focus adjusting lens disposed movably, a beam splitting elementfor splitting light beams incident on the focus adjusting lens andemerging from an object, and a first image forming lens for forming onelight beam of the light beams split by the beam splitting element intoan image. The photographing optical system guides the light beamincident on the first image forming lens and emerging from the objectonto the predetermined plane. The lens barrel also comprises a focusingestimating device having a second image forming lens for forming theother light beam of the light beams split by the beam splitting elementinto an image, at least one pair of image re-forming lenses forrespectively re-forming, into images, the light beams emerging from theobject which beams have been image-formed by the second image forminglens, and an imaging element for picking up the images obtained by atleast one pair of image re-forming lenses, the focusing estimatingdevice creating an item of focusing data for focusing the image on thepredetermined plane upon the object on the basis of the imagingpositional deviation on the imaging element between the images obtainedby at least one pair of image re-forming lenses. The lens barrel furthercomprises a moving device for moving the focus adjusting lens on thebasis of the focusing data created by the focusing estimating device.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably and an image forming lens for forming,into an image, light beams incident on the focus adjusting lens andemerging from an object. The autofocus apparatus also comprises aplurality of focusing estimating devices for creating focusing data forfocusing an image formed on a predetermined plane through thephotographing optical system, upon the object. The autofocus apparatusfurther comprises a storage device stored with a correction value forthe focusing data created by at least one of the plurality of focusingestimating devices, and a correcting device for correcting, with thecorrection value, the focusing data corresponding to the correctionvalue stored in the storage device. The autofocus apparatus stillfurther comprises a selecting device for selecting at least one of theplurality of focusing estimating devices, and a moving device for movingthe focus adjusting lens on the basis of the focusing data created bythe focusing estimating device selected by the selecting device, or therelevant corrected focusing data if the relevant focusing data has beencorrected by the correcting device.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, a beam splitting element for splittinglight beams incident on the focus adjusting lens and emerging from anobject, a first image forming lens for forming one light beam of thelight beams split by the beam splitting element into an image, and asecond image forming lens for forming the other light beam of the lightbeams split by the beam splitting element into an image. The autofocusapparatus also comprises a first focusing estimating portion having adata detecting device for detecting an item of data for focusing theimage obtained by the second image forming lens upon the object on asecond plane, a storage device stored with the data detected by the datadetecting device as a correction value when the image obtained by thefirst image forming lens is focused on the object on the first plane,and a data creating device for creating an item of focusing data forfocusing the image obtained by the first image forming lens upon theobject on the first plane. The autofocus apparatus further comprises aselecting portion for selecting at least one of the first focusingestimating portion and the second focusing estimating portion, and amoving device for moving the focus adjusting lens on the basis of thefocusing data created by the focusing estimating device selected by theselecting portion.

It is preferable that the autofocus apparatus according to the presentinvention further comprises a storage controlling device for storing thestorage device with the data detected by the data detecting portion asthe correction value when the first focus estimating portion creates thefocusing data indicating that the image obtained by the first imageforming lens is focused on the object on the first plane.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, a beam splitting element for splittinglight beams incident on the focus adjusting lens and emerging from anobject, a first image forming lens for forming one light beam of thelight beams split by the optical element into an image, and a secondimage forming lens for forming the other light beam of the light beamssplit by the beam splitting element into an image. The autofocusapparatus also comprises a first focusing estimating portion having afirst imaging element for picking up the image obtained by the firstimage forming lens and converting it into an electric signal, a leveldetecting device for detecting a level of a proper frequency componentfrom the electric signal obtained by the first imaging element, and afirst data creating device for creating an item of focusing data forfocusing the image on the first imaging element upon the object on thebasis of the frequency component level detected by the level detectingdevice. The autofocus apparatus further comprises a second focusingestimating portion having an image re-forming optical system forrespectively re-forming, into images, the light beams passing throughportions with different pupils among the light beams for forming theimage formed by the second image forming lens, a second imaging elementfor picking up the images obtained by the image re-forming opticalsystem, a positional deviation detecting device for detecting an imagingpositional deviation on the second imaging element, a storage devicestored, as a correction value, with the imaging positional deviationdetected by the positional deviation detecting device when the image onthe first imaging element is focused on the object, a correcting devicefor correcting, with the correction value stored in the storage device,the imaging positional deviation detected by the positional deviationdetecting device, and a second data creating device for creating an itemof focusing data for focusing the image on the first imaging elementupon the object on the basis of the imaging positional deviationcorrected by the correcting device. The autofocus apparatus stillfurther comprises a selecting portion for selecting at least one of thefirst focusing estimating portion and the second focusing estimatingportion, and a moving device for moving the focus adjusting lens on thebasis of the focusing data created by the focusing estimating deviceselected by the selecting portion.

The autofocus apparatus according to the present invention preferablyfurther comprises a storage controlling device for storing the storagedevice with the imaging positional deviation detected by the positionaldeviation detecting device as the correction value when the first focusestimating portion creates the focusing data indicating that the imageon the first imaging element is focused on the object.

Provided further are the storage device stored with the correction valuefor the focusing data created by at least one of the plurality offocusing estimating devices, and the correcting device for correcting,with a correction value, the focusing data corresponding to the relevantcorrection value stored in the storage device. Therefore, for example,as one of the plurality of focusing estimating devices, as in the caseof the image deviation type focusing estimating device explained in theprior art, the light beams are diverged from the photographing opticalsystem for forming the image on the imaging surface of the camera bodyand form an image in a different position from the imaging surface, andwhether or not the image on the imaging surface is focused on isestimated by use of the above image. Even in the case of using thismethod, the storage device stores, as a correction value, a deviation inthe optical positional relationship between the imaging surface of thecamera body and the surface formed with the image for estimating thefocusing. The focusing data of the corresponding focusing estimatingdevice is corrected by use of the above stored correction value, wherebya focusing accuracy is prevented from declining when using the relevantfocusing estimating device.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, and an image forming lens so movablydisposed as to form light beams incident on the focus adjusting lens andemerging from an object into an image. The autofocus apparatus alsocomprises a plurality of focusing estimating devices for creatingfocusing data for focusing an image formed on a predetermined planethrough the photographing optical system upon the object, and a positiondetecting device for detecting position data of the image forming lens.The autofocus apparatus further comprises a correcting device forcorrecting the focusing data created by at least one of the plurality offocusing estimating devices on the basis of the data about the positiondetected by the position detecting device, a selecting device forselecting at least one of the plurality of focusing estimating devices,and a moving device for moving the focus adjusting lens on the basis ofthe focusing data created by the focusing estimating device selected bythe selecting device, or the relevant corrected focusing data if therelevant focusing data has been corrected by the correcting device.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, a beam splitting element for splittinglight beams incident on the focus adjusting lens and emerging from anobject, a first image forming lens for forming one light beam of thelight beams split by the optical element into an image, and a secondimage forming lens for forming the other light beam of the light beamssplit by the beam splitting element into an image. The autofocusapparatus also comprises a first focusing estimating portion forcreating the focusing data for focusing the image obtained by the firstimage forming lens upon the object on a first plane on the basis of theimage obtained by the first image forming lens. The autofocus apparatusfurther comprises a second focusing estimating portion having a datadetecting device for detecting the data for focusing the image obtainedby the second image forming lens upon the object on a second plane, aposition detecting device for detecting the position data of the firstimage forming lens, a correcting device for correcting the data detectedby the data detecting device on the basis of an item of datacorresponding to the data about the position of the first image forminglens that has been detected by the position detecting device, which itemof data is obtained from a relationship between the position of thefirst image forming lens and the data detected by the data detectingdevice when the image on the first plane is focused on the object, and adata creating device for creating focusing data for focusing the imageobtained by the first image forming lens upon the object on the firstplane. The autofocus apparatus still further comprises a selectingportion for selecting at least one of the first focusing estimatingportion and the second focusing estimating portion, and a moving devicefor moving the focus adjusting lens on the basis of the focusing datacreated by the focusing estimating device selected by the selectingportion.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, a beam splitting element for splittinglight beams incident on the focus adjusting lens and emerging from anobject, a first image forming lens for forming one light beam of thelight beams split by the optical element into an image, and a secondimage forming lens for forming the other light beam of the light beamssplit by the beam splitting element into an image. The autofocusapparatus also comprises a first focusing estimating portion for pickingup the image obtained by the first image forming lens and converting itinto an electric signal, a level detecting device for detecting a levelof a proper frequency component from the electric signal obtained by thefirst imaging element, and a first data creating device for creating anitem of focusing data for focusing the image on the first imagingelement upon the object on the basis of the frequency component leveldetected by the level detecting device. The autofocus apparatus furthercomprises a second focusing estimating portion having an imagere-forming optical system for respectively re-forming, into images, thelight beams passing through portions with different pupils among thelight beams for forming the image formed by the second image forminglens, a second imaging element for picking up the images obtained by theimage re-forming optical system, a positional deviation detecting devicefor detecting an imaging positional deviation on the second imagingelement, a position detecting device for detecting position data of thefirst image forming lens, a correcting device for correcting imagingpositional deviation detected by the data detecting device on the basisof an imaging positional deviation corresponding to the data about theposition of the first image forming lens that has been detected by theposition detecting device, which imaging positional deviation isobtained from a relationship between the position of the first imageforming lens and the imaging positional deviation detected by thepositional deviation detecting device when the image on the firstimaging element is focused on the object, and a second data creatingdevice for creating focusing data for focusing the image on the firstimaging element upon the object on the basis of the imaging positionaldeviation corrected by the correcting device. The autofocus apparatusstill further comprises a selecting portion for selecting at least oneof the first focusing estimating portion and the second focusingestimating portion, and a moving device for moving the focus adjustinglens on the basis of the focusing data created by the focusingestimating device selected by the selecting portion.

An autofocus apparatus according to the present invention preferablycomprises a photographing optical system having at least a focusadjusting lens disposed movably, a beam splitting element for splittinglight beams incident on the focus adjusting lens and emerging from anobject, a first image forming lens so disposed movably as to form onelight beam of the light beams split by the optical element into animage, and a second image forming lens for forming the other light beamof the light beams split by the beam splitting element into an image.The autofocus apparatus also comprises a first focusing estimatingportion having a first imaging element for picking up the image obtainedby the first image forming lens and converting it into an electricsignal, a level detecting device for detecting a level of a properfrequency component from the electric signal obtained by the firstimaging element, and a first data creating device for creating an itemof focusing data for focusing the image on the first imaging elementupon the object on the basis of the frequency component level detectedby the level detecting device. The autofocus apparatus further comprisesa second focusing estimating portion having an image re-forming opticalsystem for respectively re-forming, into images, the light beams passingthrough portions with different pupils among the light beams for formingthe image formed by the second image forming lens, a second imagingelement for picking up the images obtained by the image re-formingoptical system, a positional deviation detecting device for detecting animaging positional deviation on the second imaging element, a correctingdevice for correcting a position of the image forming lens on the basisof an item of position data of the second image forming lens thatcorresponds to data about the position, detected by the positiondetecting device, of the first image forming lens, which item ofposition data is obtained from such a relationship between the positionof the first image forming lens and the position of the second imageforming lens that the imaging positional deviation on the second imagingelement disappears when the image on the first imaging element isfocused on, and a second data creating device for creating focusing datafor focusing the image on the first imaging element upon the object. Theautofocus apparatus still further comprises a selecting portion forselecting at least one of the first focusing estimating portion and thesecond focusing estimating portion, and a moving device for moving thefocus adjusting lens on the basis of the focusing data created by thefocusing estimating device selected by the selecting portion.

According to the present invention, there are provided the plurality offocusing estimating devices for creating the focusing data for focusingthe image formed on the predetermined plane through the photographingoptical system upon the object. The selecting device selects at leastone of these focusing estimating devices. The focus adjusting lens ismoved based on the focusing data created by the selected focusingestimating device. Hence, according to the present invention, forinstance, the crest climbing type focusing estimating device and theimage deviation type focusing estimating device, which have beendescribed in the prior art, are provided as the focusing estimatingdevices. To start with, the selecting device is set so that the image onthe predetermined plane is roughly focused on by use of the imagedeviation type focusing estimating device, and thereafter the image onthe predetermined plane is finely focused on by use of the focusing dataof the crest climbing type focusing estimating device. It is thereforepossible to effect the focusing quickly with the high precision.

Furthermore, according to the present invention, there are provided theposition detecting device for detecting the position data of the imageforming lens, and the correcting device for correcting the focusing datato be corrected, which data is created by the focusing estimatingdevice, on the basis of the position data of the image forming lens thathas been detected by the position detecting device. Therefore, forexample, as one of the plurality of focusing estimating devices, as inthe case of the image deviation type focusing estimating deviceexplained in the prior art, the light beams are diverged from thephotographing optical system for forming the image on the imagingsurface of the camera body and form an image in a different positionfrom the imaging surface, and whether or not the image on the imagingsurface is focused on is estimated by use of the above image. Even inthe case of using this method, the position data of the image forminglens is detected, and the deviation in the optical positionalrelationship between the imaging surface of the camera body and thesurface formed with the image for estimating the focusing, is obtainedfrom the above position data. Then, with the thus obtained deviationserving as the correction value, the focusing data of the correspondingfocusing estimating device is corrected, thereby making it possible toprevent the decline in the focusing accuracy when using the relevantfocusing estimating device.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will becomeapparent during the following discussion in conjunction with theaccompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating a crest climbing typeautofocus apparatus;

FIG. 2 is an explanatory diagram showing a relationship between a levelof a high frequency of a picture signal and a position of a focusadjusting lens;

FIG. 3 is an explanatory diagram of a principle of an image deviationtype autofocus apparatus, showing a light path when in a focused state;

FIG. 4 is an explanatory diagram showing positions of images to bepicked up by two line sensors 99 a, 99 b in FIG. 3;

FIG. 5 is an explanatory diagram of the principle of the image deviationtype autofocus apparatus, showing the light path when in a defocusedstate;

FIG. 6 is an explanatory diagram illustrating the images picked up bythe two line sensors 99 a, 99 b in FIG. 5;

FIG. 7 is an explanatory diagram of the principle of the image deviationtype autofocus apparatus, showing the light path when in the defocusedstate;

FIG. 8 is an explanatory diagram illustrating the positions of theimages picked up by the two line sensors 99 a, 99 b in FIG. 7;

FIG. 9 is a schematic block diagram of a video camera to which a priorart crest climbing type autofocus apparatus is applied;

FIG. 10 is a schematic block diagram illustrating an autofocus apparatusin a first embodiment of the present invention;

FIG. 11 is a diagram showing a modified example of the first embodimentof the present invention;

FIG. 12 is a schematic block diagram illustrating the autofocusapparatus in a second embodiment of the present invention;

FIG. 13 is a diagram showing a modified example of the second embodimentof the present invention;

FIG. 14 is a diagram showing a modified example of the second embodimentof the present invention;

FIG. 15 is a schematic block diagram illustrating the autofocusapparatus in a third embodiment of the present invention;

FIG. 16 is an explanatory diagram showing a relationship between a focallength of a photographing optical system, a distance from thephotographing optical system to an object, a dimension of the object onan imaging element, and a real dimension of the object;

FIG. 17 is a diagram showing one example of an object dimension settingdevice used in the third embodiment;

FIG. 18 is a diagram showing one example of the object dimension settingdevice used in the third embodiment;

FIG. 19 is an explanatory diagram showing a case where a plurality ofdistance measuring portions of a second focusing estimating portion areprovided;

FIG. 20 is a schematic block diagram illustrating the autofocusapparatus in a fourth embodiment of the present invention;

FIG. 21 is an explanatory diagram showing a focus area of a firstfocusing estimating portion and a focus area of the second focusingestimating portion;

FIG. 22 is a diagram showing one example of a focus area inputtingdevice used in the fourth embodiment;

FIG. 23 is an explanatory diagram showing how a focus area settingdevice operates;

FIG. 24 is an explanatory diagram showing how the focus area settingdevice operates;

FIG. 25 is a diagram showing one example of the focus area inputtingdevice used in the fourth embodiment;

FIG. 26 is a diagram showing one example of the focus area inputtingdevice used in the fourth embodiment;

FIG. 27 is an explanatory diagram showing a case where a plurality offocus areas of the second focusing estimating portion are provided;

FIG. 28 is a schematic block diagram illustrating the autofocusapparatus in a fifth embodiment of the present invention;

FIG. 29 is a schematic block diagram illustrating a TV camera in a sixthembodiment of the present invention;

FIG. 30 is an explanatory flowchart showing how the TV camera shown inFIG. 29 performs an autofocus operation;

FIG. 31 is an explanatory diagram of a principle of an image deviationtype autofocus system, showing the light path when in a focused state;

FIG. 32 is an explanatory diagram showing positions of images picked upby the two line sensors in FIG. 31;

FIG. 33 is an explanatory diagram of the principle of the imagedeviation type autofocus system, showing the light path when in adefocused state;

FIG. 34 is an explanatory diagram illustrating the positions of theimages picked up by the two line sensors in FIG. 33;

FIG. 35 is an explanatory diagram of the principle of the imagedeviation type autofocus system, showing the light path when in adefocused state;

FIG. 36 is an explanatory diagram showing the positions of the imagespicked up by the two line sensors in FIG. 35;

FIG. 37 is a schematic block diagram illustrating the TV camera in aseventh embodiment of the present invention;

FIG. 38 is a schematic block diagram illustrating the TV camera in aneighth embodiment of the present invention;

FIG. 39 is a schematic block diagram illustrating the TV camera in aninth embodiment of the present invention;

FIG. 40 is a schematic block diagram illustrating the TV camera in atenth embodiment of the present invention;

FIG. 41 is a schematic block diagram illustrating the TV camera in aneleventh embodiment of the present invention;

FIG. 42 is an explanatory flowchart showing the operation of theautofocus apparatus illustrated in FIG. 41;

FIG. 43 is an explanatory flowchart showing an operation of the firstfocusing estimating portion illustrated in FIG. 41;

FIG. 44 is an explanatory flowchart showing an operation of the secondfocusing estimating portion illustrated in FIG. 41;

FIG. 45 is an explanatory flowchart showing an operation of a defocusstorage device shown in FIG. 41;

FIG. 46 is a schematic block diagram illustrating the autofocusapparatus in a twelfth embodiment of the present invention;

FIG. 47 is an explanatory flowchart showing the operation of theautofocus apparatus illustrated in FIG. 46;

FIG. 48 is an explanatory flowchart showing the operation of the firstfocusing estimating portion illustrated in FIG. 46;

FIG. 49 is an explanatory flowchart showing the operation of the secondfocusing estimating portion illustrated in FIG. 46;

FIG. 50 is a schematic block diagram showing the autofocus apparatus ina thirteenth embodiment of the present invention; and

FIG. 51 is an explanatory diagram showing a relationship between a levelof a high frequency component of a picture signal and a focus adjustinglens.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the present invention will hereinafter be describedwith reference to the drawings.

FIG. 10 is a schematic block diagram illustrating an autofocus apparatusin one embodiment of the present invention.

The autofocus apparatus in this embodiment includes, as illustrated inFIG. 10, a photographing optical system 1, a first focus estimating part2, a second focusing estimating part 3, a focusing method selectingdevice 4, a motor 5, and a motor driving device 6.

The photographing optical system 1 is constructed of four lens unitssuch as a focus adjusting lens 11, a variable magnification lens 12, acorrecting lens 13, and an image forming lens 14. This construction istypical of a zoom lens for a TV camera. In the photographing opticalsystem 1 used in this embodiment, an optical element (e.g., a beamsplitter) 15 for splitting light beams and a stop 16 are interposed inbetween the correcting lens 13 and the image forming lens 14. Note thatthe optical element 15 is disposed anterior to the stop 16 so that thelight beams can be transmitted to the second focusing estimating part 3irrespective of an aperture quantity of an aperture stop of thephotographing optical system 1 in this embodiment.

The first focusing estimating part 2 estimates focusing by a so-calledcrest climbing method. The first focusing estimating part 2 includes animaging element 21 for picking up an image formed by the image forminglens 14 of the photographing optical system 1 and converting it into anelectric signal, and a picture signal making device 22 for generating apicture signal corresponding to the electric signal transmitted from theimaging element 21. The first focusing estimating part 2 also includes afocusing estimated value creating device 23 for creating an item of data(a first focusing estimated value) for focusing the image formed on theimaging element 21 on the basis of the picture signal given from thepicture signal making device 22. Note that the electric signal outputtedfrom the imaging element 21 is, as shown in FIG. 10, also used forgenerating a picture signal of a video camera.

Next, a first focusing estimated value created by the focusing estimatedvalue creating device 23 will be explained. As described in the priorart, the picture signal is, it can be assumed, formed by synthesizingsine waves of a plurality of frequencies. Then, it is well known that alevel of high frequency component of the picture signal, as illustratedin FIG. 2, rises more steeply according as a degree of sharpness of theimage formed on the imaging element 21 increases, i.e., the focusadjusting lens 11 moves closer to a focusing point A, and this levelreaches a peak when the image on the imaging element 21 is focused on.Subsequently, the focusing estimated value creating device 23 selects aproper high frequency component in consideration of an S/N ratio of thepicture signal as well as of an imaging performance of the photographingoptical system 1, out of the picture signal obtained by the picturesignal making device 22. Then, the focusing estimated value creatingdevice 23 creates a focusing estimated value by monitoring a level ofthis frequency component at a predetermined sampling interval. Forexample, when the level of the selected frequency component rises, it isestimated that the focus adjusting lens 11 is moving in such a directionas to approach a focusing point. Further, when the level of the selectedfrequency component lowers, it is estimated that the focus adjustinglens 11 is moving in such a direction as to get away from the focusingpoint. Then, when the level of the selected frequency component existswithin a predetermined range (shown by, e.g., ΔV in FIG. 2) from thepeak value, it is estimated that the image on the imaging element 21 isfocused on.

The second focusing estimating part 3 estimates focusing by a so-calledimage deviation method. The second focusing estimating part 3 comprisesa mirror 31 for reflecting the light beam split by the optical element15, toward a predetermined direction, and an image forming lens 32 forforming light beams incident via the mirror 31 into a conjugate image.The second focusing estimating part 3 further comprises image re-forminglenses 33 a, 33 b for forming some of the light beams image formed bythe image forming lens 32, again into images, line sensors 34 a, 34 bfor respectively picking up the images formed by the image re-forminglenses 33 a, 33 b and converting them into electric signals, an imageprocessing device 35, and a focusing estimation selecting device 36.

The image forming lens 32 is disposed so that the light beams incidentvia the mirror 31 are image-formed on a predetermined focal surface 37when the image on the imaging element 21 is focused on. The imagere-forming lenses 33 a, 33 b are disposed in positions substantiallysymmetric with respect to the optical axis of the image forming lens 32.More specifically, the image re-forming lenses 33 a, 33 b are sodisposed as to individually re-form the images of the light beamspassing through portions having different pupils in the optical systemconsisting of the focus adjusting lens 11, the variable magnificationlens 12, the correcting lens 13 and the image forming lens 32, among thelight beams for forming the image formed by the image forming lens 32.The line sensors 34 a, 34 b are disposed in the positions substantiallysymmetric with respect to the optical axis of the image forming lens 32and on a predetermined focal surface of the image re-forming lenses 33a, 33 b corresponding to each other. The image processing device 35executes the image processing based on the electric signals transmittedrespectively from the line sensors 34 a, 34 b. The focusing estimatedvalue creating device 36 creates an item of data (a second focusingestimated value) for focusing the image formed on the imaging element 21on the basis of the signal transmitted from the image processing device35.

Next, the second focusing estimated value created by the focusingestimated value creating device 36 will be explained. As stated in theprior art, when the light beams traveling through the image forming lens32 are focused on the predetermined focal surface 37, some of the lightbeams are again formed on the line sensors 34 a, 34 b by the imagere-forming lenses 33 a, 33 b. Hence, if focused on the predeterminedfocal surface 37, the images picked up by the two line sensors 33 a, 33b are formed in substantially coincident positions on the line sensors.On the other hand, when the light beams passing through the imageforming lens 32 are focused on anterior to the predetermined focalsurface 37 (which is a so-called rear focus state), there must be adeviation between the images picked up by the two line sensors 34 a, 34b. Also, when the light beams passing through the image forming lens 32are focused on posterior to the predetermined focal surface 37 (which isa so-called front focus state), there must be a deviation in a directionopposite to the one in the rear focus state between the images picked upby the two line sensors 34 a, 34 b. Then, the focusing estimated valuecreating device 36 detects a deviation quantity and a deviatingdirection between the images picked up by the line sensors 34 a, 34 b,and, based on the data thereof, creates a moving direction and a movingquantity, or a defocus quantity and a defocus direction (a secondfocusing estimated value) of the focus adjusting lens 11, which areneeded for focusing on the predetermined focal surface 37. Note that thesecond focusing estimated value is created at the interval of apredetermined time in consideration of a processing speed, etc. of theimage processing device 35.

The focusing method selecting device 4 selects at least one of the firstfocusing estimated value created by the first focusing estimating part 2and the second focusing estimated value created by the second focusingestimating part 3. In accordance with this embodiment, referring firstto the second focusing estimated value, if the required-for-focusingmoving quantity of the focus adjusting lens 11 is larger than athreshold value, the second focusing estimated value is set to beselected. Whereas if smaller than the threshold value, the firstfocusing estimated value is set to be selected. Note that this thresholdvalue may also be set arbitrarily by a photographer and so forth throughinputting from outside.

The motor driving device 6 drives the motor 5 on the basis of thefocusing estimated value selected by the focusing method selectingdevice 4. Based on a command given from the motor driving device 6, themotor 5 moves the focus adjusting lens 11 forward and backward in theoptical-axis direction of the photographing optical system 1.

Incidentally, the focusing estimated value creating devices 23, 36 andthe focusing method selecting device 4 are integrally constructed of,e.g., a CPU (Central Processing Unit), etc.

Next, an operation of the autofocus apparatus in this embodiment will bedescribed.

To start with, upon an incidence of the light beams upon thephotographing optical system 1 from an object, the first focusingestimating part 2 creates the first focusing estimated value on thebasis of the light beams obtained via the image forming lens 14 in thephotographing optical system 1. Further, the second focusing estimatingpart 3 creates the second focusing estimated value based on the lightbeams split by the optical element 15 in the photographing opticalsystem 1.

Next, the focusing method selecting device 3, referring to the secondfocusing estimated value, judges whether or not therequired-for-focusing moving quantity or defocus quantity of the focusadjusting lens 11 is larger than the threshold value. Then, if therequired-for-focusing moving quantity or defocus quantity of the focusadjusting lens 11 is larger than the threshold value, the secondfocusing estimated value is selected. Whereas if smaller than thethreshold value, the first focusing estimated value is selected.

Next, the motor driving device 6 drives the motor based on the focusingestimated value selected by the focusing method selecting device 4. Forinstance, if the second focusing estimated value is selected by thefocusing method selecting device 4, the motor driving device 6 drivesthe motor 5 to move the focus driving lens 11 in the moving directionwith the moving quantity that are indicated by the selected secondfocusing estimated value. Further, for example, if the first focusingestimated value is selected by the focusing method selecting device 4,and when estimating that the focus adjusting lens 11 is moving in such adirection as to approach the focusing point, the motor driving device 6drives the motor 5 to keep a rotating direction of the motor 5 as it is.Moreover, when estimating that the focus adjusting lens 11 is moving insuch a direction as to get away from the focusing point, the motordriving device 6 drives the motor 5 to reverse the rotating direction ofthe motor 5.

The motor driving device 6 continues to drive the motor 5 till it isestimated that the first focusing estimated value is selected by thefocusing method selecting device 4 and a content of the first focusingestimated value indicates an in-focus state. The image on the imagingelement 21 is thereby focused on.

In accordance with the first embodiment of the present invention, thefirst focusing estimating part 2 creates the first focusing estimatedvalue by use of the so-called crest climbing method, and the secondfocusing estimating part 3 creates the second focusing estimated valueby use of the so-called image deviation method. Further, the focusingmethod selecting device 4 selects the second focusing estimated valuewhen the second focusing estimated value is larger than the thresholdvalue, and selects the first focusing estimated value when smaller thanthe threshold value. Then, the motor driving device 6, based on thefocusing estimated value selected by the focusing method selectingdevice 4, drives the motor 5 to move the focus adjusting lens 11. Withthis operation, to begin with, the image on the imaging element 21 isroughly focused on by use of the second focusing estimated value, andthereafter the image on the imaging element 21 is finely focused on byuse of the first focusing estimated value. Accordingly, in accordancewith the first embodiment, the image on the imaging element 21 can befocused on quickly with a high accuracy. Further, the high accuracy isnot required of the second focusing estimating part 3 using the imagedeviation method, and hence the costs can be restrained from rising.

Moreover, in the first embodiment of the present invention, a focallength of the optical system for forming images for detecting the imagedeviation on the line sensors 34 a, 34 b in the second focusingestimating part 3, is a synthetic focal length of the focus adjustinglens 11, the variable magnification lens 12, the correcting lens 13 andthe image forming lens 32. On the other hand, a focal length of theoptical system for forming an image for the picture signal on theimaging element 21, is a synthetic focal length of the focus adjustinglens 11, the variable magnification lens 12, the correcting lens 13 andthe image forming lens 14. Therefore, the focal lengths of the opticalsystem for forming the images for detecting the image deviation and ofthe optical system for forming the image for the picture signal, arevaried by changing configurations of the image forming lenses 14 and 32,videlicet, the sizes of the images formed respectively by the individualoptical systems can be changed. For instance, the image forming lens 32is constructed to enlarge the images for detecting the image deviationby increasing the focal length of the optical system for forming theimages for detecting the image deviation, whereby pixel pitches of thelines sensors 34 a, 34 b become finer relatively to the above images.Hence, it is feasible to focus even a minute object. Further, forexample, the image forming lens 32 is constructed to diminish the imagesfor detecting the image deviation by shortening the focal length of theoptical system for forming the images for detecting the image deviation,whereby sizes of these images become smaller relatively to the linesensors 34 a, 34 b. Therefore, it is possible to detect a largerquantity of image deviation. Even if the focus adjusting lens ispositioned far from the focusing point (which is a so-called largelydefocused state), the focusing point can be thereby quickly detected.Also, the apparatus can be downsized.

By the way, in the image deviation type autofocus apparatus used for agenerally commercially available still camera, etc., the image deviationis detected by use of an image in the vicinity of the center among theimages formed by the photographing optical system. Accordingly, in thisimage deviation type autofocus apparatus, the focusing can be attainedonly in the vicinity of the center of an area (hereinafter also referredto as a photographic area) to be photographed by the photographingoptical system. It is because the sizes of the line sensor and of theimage re-forming lens employed for detecting the image deviation arerestricted due to problems in terms of a size of the camera body andcosts thereof, etc. Contrastingly in the crest climbing type autofocusapparatus used for the video camera, the focusing is effected by use ofthe images on the imaging element, and therefore a focus area can bechanged comparatively easily. Herein, the focus area is an area wherethe data for focusing is created within the photographic area. In thisembodiment, the focus area corresponds to the area where the data forfocusing the image on the relevant area on a corresponding object in thearea on the imaging element 21. Hence, when the general image deviationtype autofocus apparatus is employed for the second focusing estimatingpart 3, as illustrated in FIG. 11, it is preferable that a focus areaselecting device 70 for selecting a position of the focus area beprovided. Then, in the focusing method selecting device 4, only when thefocus area selecting device 70 selects the center of the photographicarea as a focus area, at least one of the first focusing estimated valueand the second focusing estimated value is selected in the proceduresstated in this embodiment, and it is preferable that only the firstfocusing estimated value be selected when a portion other than thecenter in the photographic area is selected as the focus area by thefocus area selecting device 70. With this operation, it is feasible tofocus the image corresponding to the object existing in the plurality ofareas within the photographic area, among the images on the firstimaging element 21.

Further, in recent years, there have been developed some of the imagedeviation type autofocus apparatuses, which are capable of setting thefocus area in the plurality of portions within the photographic area.This may correspond to, e.g., a multi-area focus detecting apparatusdisclosed in Japanese Patent Laid-Open Application No. 6-308379. Inthose apparatuses, four or more (even-numbered) pieces of line sensorsand image re-forming lenses are provided in the image deviation typeautofocus apparatus illustrated in FIG. 3 in the statement of the priorart, and images of a plurality of portions are taken out of the imagesformed by the image forming optical system, thereby detecting adeviation of each of the images. If the above autofocus apparatus isused for the second focusing estimating part 3, it is possible to employthe crest climbing type and the image deviation type in combination tofocus the image corresponding to the object existing in the relevantportion with respect to the plurality of portions within thephotographic area.

Note that the focusing method selecting device 4 in the first embodimentof the present invention has been explained so far by way of the devicefor selecting the first focusing estimated value when the secondfocusing estimated value created by the second focusing estimating part3 is smaller than the threshold value, and selecting the second focusingestimated value when larger than the threshold value. The presentinvention is not, however, limited to this. The focusing methodselecting device may, if, for example, any one of the first and secondfocusing estimated values is useless, select the other estimated value.Herein, “being useless” implies such a case that the image on theimaging element 21 can not be focused on with that estimated value. Itis because there must be a case where the focusing point can not bedetected depending on the object on account of the fact that the crestclimbing type and the image deviation type have their principlesabsolutely different from each other.

In the first focusing estimating part 2 adopting the crest climbingmethod, the focusing point is detected with reference to the level ofthe high frequency component of the picture signal. Therefore, if theobject is, e.g., dark, an S/N ratio of the picture signal declinesenough not to perform the focusing with a high precision. Further, whenthe object is on the movement, it might happen that the peak of the highfrequency component level can not be detected however long the time mayelapse. In such a case, the focusing method selecting apparatus judgesthat the first focusing estimated value is useless and therefore selectsthe second focusing estimated value. On the other hand, in the secondfocusing estimating part 3 adopting the image deviation method, thefocusing point is detected based on a deviating direction and adeviation quantity between the images picked up respectively by the linesensors 34 a, 34 b, and hence, if the object has a streak pattern, itmight happen that a plurality of image deviation quantities aredetected. In such a case, the focusing method selecting device judgesthat the second focusing estimated value is useless, and thereforeselects the first focusing estimated value. Thus, if any one of thefirst and second focusing estimated values is useless, the otherestimated value is selected, thereby ensuring the focusing on theobject.

Next, a second embodiment of the present invention will be describedwith reference to the drawings.

FIG. 12 is a schematic block diagram illustrating the autofocusapparatus in the second embodiment of the present invention. Note thatthe elements having the same functions as those in the first embodimentshown in FIG. 10 are marked with the like or corresponding numerals inthe second embodiment of the present invention, and the detailedexplanations thereof are omitted.

A different point of the autofocus apparatus in the second embodimentshown in FIG. 12 from the first embodiment shown in FIG. 10, is that afocusing method selecting device 4 a is employed in place of thefocusing method selecting device 4, and that an aperture value detectingdevice 80 for detecting an aperture value of the stop 16 of thephotographing optical system 1. Other configurations are basically thesame as those in the first embodiment.

A difference of the focusing method selecting device 4 a from thefocusing method selecting device 4 used in the first embodiment, is thatwhen the aperture value sent from the aperture value detecting device 80is under a predetermined threshold value, the second focusing estimatedvalue is selected irrespective of whether or not therequired-for-focusing moving quantity, obtained from the second focusingestimated value, of the focus adjusting lens 11 is larger than thethreshold value. The following is an elucidation of the reason why theaperture value is referred to for selecting the focusing method. Whenthe stop 16 of the photographing optical system 1 is stopped down, adepth of field becomes larger, and, with this larger depth of field, acrest of the high frequency component level of the picture signalobtained by the imaging element 21 becomes gentle. This implies anenlargement of a range Δd of the position of the focus adjusting lens 11versus a level range ΔV in which to be judged as an in-focus state inFIG. 2. On the other hand, the stop does not transmit the light beamsused for the second focusing estimating part 3, and therefore therequired-for-focusing moving quantity, obtained from the second focusingestimated value, of the focus adjusting lens 11 undergoes no influenceby the stop. Accordingly, it might be considered that the focusingaccuracy in the first focusing estimating part 3 adopting the crestclimbing method is inferior to the focusing accuracy in the secondfocusing estimating part 3 adopting the image deviation method,depending on the aperture value (a degree of stop-down). Then, thefocusing method selecting device 4 a in the second embodiment selectsthe second focusing estimated value when the aperture value is under thepredetermined threshold value regardless of the required-for-focusingmoving quantity, obtained from the second focusing estimated value, ofthe focus adjusting lens 11. Others are the same as those in thefocusing method selecting device 4 employed in the first embodiment.

In accordance with the second embodiment of the present invention, theaperture value of the photographing optical system 1 is referred to forselecting the focusing method, and hence, upon the stop-down of the stop16, if the focusing accuracy in the first focusing estimating part 2adopting the crest climbing method is inferior to the focusing accuracyin the second focusing estimating part 3 adopting the image deviationmethod, the second focusing estimated value can be selected. The optimalfocusing method in terms of the focusing accuracy and the focusing speedcan be thereby selected.

Incidentally, the second embodiment has been explained so far by way ofthe one requiring the reference to the aperture value of thephotographing optical system 1 on the occasion of the selection of thefocusing method. The present invention is not, however, confined tothis, and there may be referred to other factors exerting influencesupon the depth of field.

FIG. 13 is a diagram showing a modification of the second embodiment. Inthe autofocus apparatus illustrated in FIG. 13, positions of the focusadjusting lens 11 and of the variable magnification lens 12 are alsoreferred to in addition to the aperture value of the stop 16. This is aconsideration that there exists an optical system with a depth of field,i.e., an image forming performance largely changed depending on theposition of the variable magnification lens 12 as well as on theposition of the focus adjusting lens 11. A focusing method selectingdevice 4 b refers to an aperture value of the stop 16 that istransmitted from an aperture value detecting device 8, a position of thevariable magnification lens 12 that is transmitted from a variablemagnification lens position detecting device 81, and a position of thefocus adjusting lens 11 that is transmitted from a focus adjusting lensposition detecting device 82. The focusing method selecting device 4 bthen reads an image forming performance corresponding to those valuesfrom an image forming performance storage device 83. Subsequently, whenjudging from the thus read image forming performance that the focusingaccuracy in the first focusing estimating part 2 adopting the crestclimbing method is inferior to the focusing accuracy in the secondfocusing estimating part 3 adopting the image deviation method, thesecond focusing estimated value is selected irrespective of therequired-for-focusing moving quantity, obtained from the second focusingestimated value, of the focus adjusting lens 11.

FIG. 14 is a diagram showing another modification of the secondembodiment. In the autofocus apparatus illustrated in FIG. 14, there isfurther referred to kinds of attached optical accessaries. Herein, theoptical accessaries include converters such as a tele-converter and awide converter, attachments such as a wide attachment and a fish-eyeattachment, filters, close-up lenses, and extenders, which are attachedto the photographing optical system 1. Even when those opticalattachments are attached thereto, the depth of field, viz., the imageforming performance largely varies depending upon the kinds thereof asthe case may be. Then, the focusing method selecting device 4 c refersto existence and non-existence and kinds of the optical accessaries,which are transmitted from an optical accessary attached state detectingdevice 84 in addition to the aperture value of the stop 16, and thepositions of the variable magnification lens 12 and of the focusadjusting lens 11, and reads the image forming performance correspondingto these values from the image forming performance storage device 83 a.Then, the estimated value is selected by the same method as that of thefocusing method selecting device 4 b of the autofocus apparatus shown inFIG. 13. Note that the kinds of the optical accessaries can bedetermined by providing the optical accessaries with identificationdata.

Next, a third embodiment of the present invention will be discussed withreference to the drawings.

FIG. 15 is a schematic block diagram illustrating the autofocusapparatus in the third embodiment of the present invention. FIG. 16 isan explanatory diagram showing a relationship between a focal length ofthe photographing optical system, a distance from the photographingoptical system to the object, a dimension of the object on the imagingelement, and a real dimension of the object. FIG. 17 is a diagramshowing one example of an object dimension setting device used in thethird embodiment. Note that the elements having the same functions asthose in the first embodiment shown in FIG. 10 are marked with the likeor corresponding numerals in the third embodiment of the presentinvention, and the detailed explanations thereof are omitted.

A different point of the autofocus apparatus in the third embodimentillustrated in FIG. 15 from the first embodiment shown in FIG. 10, isthat there are provided an object dimension setting device 71, an objectdimension calculating device 72, a focusing object controlling device73, a focus adjusting lens encoder 74 for detecting a position of thefocus adjusting lens 11, and a variable magnification lens encoder 75for detecting a position of the variable magnification lens 12. Otherconfigurations are basically the same as those in the first embodiment.

The object dimension setting device 71 sets a dimension (e.g.,lengthwise size×crosswise size) of the object to be focused on (focusingobject) with inputting by the photographer or the like. In theembodiment illustrated in FIG. 17, a pointer 71 b on a knob 71 aconsisting of a rotary type variable resistor is set to an arbitraryvalue of a scale 71 c, thus setting this value to a dimension of thefocusing object. Herein, the value of the scale 71 c represents acrosswise size of the focusing object. The object dimension settingdevice 71 outputs, to the focusing object controlling device 73, aresistance value of the knob 71 a, i.e., a signal corresponding to thevalue of the scale 71 c which value is pointed by the pointer 71 b onthe knob 71 a. Note that a slide type variable resistor and amulti-stage switch or an encoder, etc. may also be employed as asubstitute for the knob 71 a consisting of the rotary type variableresistor in FIG. 17. Further, this dimension may be displayed on afinder of the video camera or recorded in a record picture so that thephotographer is able to grasp the dimension of the focusing object whichhas been set by himself or herself.

The object dimension calculating device 72 calculates the real dimensionof the object on the basis of a distance from an image-side principalpoint of the photographing optical system 1, a distance from anobject-side principal point of the photographing optical system 1, and adimension of the object on the imaging element 21. Referring to FIG. 16,the real dimensions Y₁ and Y₂ of the objects Z₁, Z₂ are expressed by thefollowing formulae:Y ₁ =a ₁ ×y ₁ ÷b ₁Y ₂ =a ₂ ×y ₂ ÷b ₂where b₁, b₂ are the distances from the image side principal point H′ ofthe photographing optical system 1 to the image surface, a₁, a₂ are thedistances from the object-side principal point H of the photographingoptical system 1 to the objects Z₁, Z₂, and y₁, y₂ are the dimensions ofthe objects Z₁, Z₂ on the imaging element 21.

In the photographing optical system 1 in the third embodiment, thedistances b₁, b₂ from the image side principal point H′ of thephotographing optical system 1 to the image surface are obtained basedon data about a position of the variable magnification lens 12 whichposition is detected by the variable magnification lens encoder 75.

Further, the distances a₁, a₂ from the photographing optical system 1 tothe objects Z₁, Z₂ are calculated based on a deviating direction and adeviation quantity (a second focusing estimated value) in terms ofimaging positions between the images picked up respectively by the linesensors 33 a, 33 b in the second focusing estimating part 3, and on dataabout a position of the focus adjusting lens 11 which position isdetected by the focus adjusting lens encoder 74. Note that if the objecton the imaging element 21 is in a state approximate to the in-focusstate, the distance from the object-side principal point of thephotographing optical system can be obtained based on the position ofthe focus adjusting lens 11. The third embodiment is, however,constructed such that the distance from the photographing optical system1 to the object can be obtained even in a defocused state of the objecton the imaging element 21 by use of the second focusing estimated valuecreated by the image deviation method and the positional data of thefocus adjusting lens 11.

Moreover, the dimensions of the objects Z₁, Z₂ on the imaging element 21can be obtained by executing proper image processing on the image dataof the imaging element 21. For instance, the dimensions of the objectsZ₁, Z₂ on the imaging element 21 can be acquired by emphasizing theobject out by using color signals of the image data and binarizing theimage or by executing a process such as detecting an outline and soforth. Furthermore, if the object on the imaging element 21 is in thestate approximate to the in-focus state, the dimension of the object onthe imaging element 21 can be obtained by recognizing that a portion,with a large variation in contrast, of the picture signal generated bythe picture signal making device 22 is defined as a peripheral portionof the object.

The focusing object controlling device 73 compares the object realdimension calculated by the object dimension calculating device 72 withthe object dimension set by the object dimension setting device 71.Then, if the two dimensions are substantially the same, the first andsecond focusing estimating parts 2 and 3 are controlled to focus on theobject. That is, the first and second focusing estimating parts 2 and 3are controlled to create the first and second estimated values withrespect to the object. Whereas if the above two dimensions are notsubstantially the same, the first and second focusing estimating parts2, 3 are controlled to focus on an object exclusive of the objectconcerned among the images on the imaging element 21. That is, the firstand second focusing estimating parts 2, 3 are controlled to create thefirst and second focusing estimated values with respect to the objectother than the object concerned. Note that this focusing objectcontrolling device 73 is constructed of, e.g., a CPU (Central ProcessingUnit) or the like integrally with the focusing estimated value creatingdevices 23, 36 and the focusing method selecting device 4.

Next, an operation of the third embodiment will be described. The objectdimension setting device 71 sets the dimension of the focusing objectand transmits data about this dimension to the focusing objectcontrolling device 73. On the other hand, the object dimensioncalculating device 72 calculates the object real dimension to beconsidered as the first and second estimated values created by the firstand second focusing estimating parts 2 and 3, and transmits data aboutthis dimension to the focusing object controlling device 73.

The focusing object controlling device 73 compares the object realdimension calculated by the object dimension calculating device 72 withthe object dimension set by the object dimension setting device 71.Then, if the two dimensions are substantially the same, the objectconcerned is judged to be the focusing object, and the first and secondfocusing estimating parts 2 and 3 are controlled to successively createthe first and second focusing estimated values with respect to theobject concerned. Whereas if not substantially the same, the objectconcerned is judged not to be the focusing object, and the first andsecond focusing estimating parts 2 and 3 are controlled to create thefirst and second focusing estimated values with respect to an objectother than the object concerned. Then, the above comparison is repeatedtill the focusing object is detected from the images on the imagingelement 21. Note that other operations in the third embodiment arefundamentally the same as those in the first embodiment.

In accordance with the third embodiment of the present invention, thefocusing on the object is carried out only when the object realdimension calculated by the object dimension calculating device 72 issubstantially coincident with the dimension set by the object dimensionsetting device 71. The autofocusing operation can be thereby performedwith respect to only the object having the dimension substantiallycoincident with the dimension of the focusing object. It is thereforefeasible to prevent the focusing on an unexpected object and an objecttraversing in front of the object concerned.

Moreover, the photographer is capable of varying the dimension of thefocusing object corresponding to a condition when photographed by use ofthe object dimension setting device 71 by which the photographer can setthe dimension of the focusing object.

Note that the focusing object is judged by making use of the crosswisedimension of the object in the third embodiment, but the presentinvention is not limited to this. According to the present invention,the focusing object can be judged by making use of dimensions in theperpendicular and oblique directions. In this case, the range of theobject to be photographed can be further widened.

Also, in the third embodiment, the object dimension setting device 71has been discussed so far as the one by which the photographer iscapable of inputting the dimension of the focusing object. The presentinvention is not, however, confined to this. For instance, it may bepracticed that objects (human being, vehicle, etc.) generally exhibitinga high possibility of being focused may be expressed in graphics likesymbols and characters, and the photographer arbitrarily selects any oneof these graphics, thereby setting the dimension of the focusing object.For example, when the human being is selected, the dimension of thefocusing object is set to 50 cm that can be considered as a standardbody breadth of the human being. In this case, the graphics representingthe human being, wire netting and vehicle are displayed on the finder ofthe video camera, and are selectable by a switch provided in anotherposition different from the finder and a touch panel provided on thefinder.

Further, in accordance with the third embodiment, the focusing objectcontrolling device 73 has been explained so far as the one constructedto focus the object concerned only when the object real dimensioncalculated by the object dimension calculating device 72 issubstantially the same as the dimension set by the object dimensionsetting device 71, the present invention is not, however, limited tothis. For instance, if the object real dimension calculated by theobject dimension calculating device 72 is substantially the same as thedimension set by the object dimension setting device 71, the focusing onthe object concerned may not be performed. With this arrangement, thefocusing on a specified object (e.g., wire netting or the like) is notallowed. Further, for example, the photographer is able to make aselection about whether the focusing is effected with the dimension setby the object dimension setting device, and, whether to focus on theobject concerned may be judged based on a selected content. In thiscase, the object dimension setting device is preferably capable ofselecting the focusing object and non-focusing objects (which must notbe focused on) as illustrated in FIG. 18. In the embodiment shown inFIG. 18, a pointer 71 e of a rotary type variable resistor 71 d is setto an arbitrary value of a focusing scale 71 f or a non-focusing scale71 g, thus setting this value to a dimension of the focusing object orthe non-focusing object. Herein, each of the values of the scales 71 f,71 g represents a crosswise size of the object. This object dimensionsetting device outputs, to the focusing object controlling device,resistance values of the variable resistor 71, viz., signalscorresponding to a scale type (the focusing scale 71 f or thenon-focusing scale 71 g) pointed by the pointer 71 e of the variableresistor 71 d and to a value of the scale.

Further, in accordance with the third embodiment, there has beendescribed the way how the lens position is measured by the encoders 74,75 for obtaining the positional data of the variable magnification lens12 and of the focus adjusting lens 11. However, if open roof control isexecuted by use of a stepping motor as a driving source for each lens,it is possible to grasp the lens position at all times without anyencoder.

Moreover, as explained in the first embodiment, there are developed someof even the image deviation type autofocus apparatuses, which arecapable of setting the focus area in a plurality of portions within thephotographic area. If that kind of autofocus apparatus is used for thesecond focusing estimating part 3 in the third embodiment, the crestclimbing method and the image deviation method are used in combinationfor focusing the image corresponding to the object that exists in theportion concerned in the plurality of portions within the photographicarea. Also, the real dimension of the object can be thereby measured.This makes it feasible to focus on any one of the objects by letting thephotographer select the focus area (e.g., the central portion of thephotographic area) when, for example, as illustrated in FIG. 19, objectsY₃, Y₄ each having substantially the same dimension appear on thephotographic area.

Note that the focusing method selecting device 4 and the focus estimatedvalue creating device 23 of the first estimating part 2 are omitted, andthe picture signal transmitted from the picture signal making device 22of the first estimating part 2 may be used exclusively for measuring thedimension of the object on the imaging element 21 in the thirdembodiment. In this case, the image on the imaging element 21 is focusedon the corresponding object on the basis of the second focusingestimated value created by the second focusing estimating part 3.

Next, a fourth embodiment of the present invention will be discussedwith reference to the drawings.

FIG. 20 is a schematic block diagram illustrating the autofocusapparatus in a fourth embodiment of the present invention. FIG. 21 is anexplanatory diagram showing a focus area of the first focusingestimating part and a focus area of the second focusing estimating part.FIG. 22 is a diagram showing one example of a focus area inputtingdevice used in the fourth embodiment. FIG. 23 is an explanatory diagramshowing an operation of a focus area setting device. Note that theelements having the same functions as those in the first embodimentshown in FIG. 10 are marked with the like or corresponding numerals inthe fourth embodiment of the present invention, and the detailedexplanations thereof are omitted.

A different point of the autofocus apparatus in the fourth embodimentillustrated in FIG. 20 from the first embodiment shown in FIG. 10, isthat there are provided a focus area size inputting device 76, a focusarea setting device 77 and a focus area display device 78. Otherconfigurations are basically the same as those in the first embodiment.

The first focusing estimating part 2 using the crest climbing methodcreates the first focusing estimated value based on the picture signalobtained by the imaging element 21. Therefore, as illustrated in FIG.21, the first focusing estimated value is creased based on the picturesignals by fetching the picture signals on the imaging element 21, thesesignals corresponding to arbitrary areas in the photographic area 21 aphotographed by the photographing optical system 1, e.g., areas 112 aand 112 b. That is, the first focusing estimating part 2 is capable ofarbitrarily varying the focus area. On the other hand, the focus area ofthe second focusing estimating part 3 using the image deviation methodis set in predetermined area depending on sizes of the image forminglens 32, the line sensors 34 a, 34 b and the image re-forming lenses 33a, 33 b. Accordingly, the focus area of the second focusing estimatingpart 3 is not variable. In the autofocus apparatus in the fourthembodiment, the focus area of the second focusing estimating part 3 is,as illustrated in FIG. 21, set in a vicinity-of-center 111 of thephotographic area 21 a. Further, the image processing device 35 executespredetermined image processing, thereby subdividing the focus area 111into a plurality of unit areas 111 a-111 i. Then, an image deviation isdetected in each of the unit areas 111 a-111 i.

The focus area size inputting device 76 is designed so that thephotographer inputs data about the focus area of the first focusingestimating part 2. In an example shown in FIG. 22, a pointer 76 b of aknob 76 a consisting of a rotary type variable resistor is set to anarbitrary position of a scale 76 c, thus designating a size of the focusarea. For example, when the pointer 76 b is set to “standard” of thescale 76 c, the focus area of the first focusing estimating part 2becomes substantially the same as the size of the focus area of thesecond focusing estimating part 3. Further, when the pointer 76 b of thescale 76 c is set on a “smaller area” side than the “standard area”position of the scale 76 c, the focus area of the first focusingestimating part 2 becomes smaller than the focus area of the secondfocusing estimating part 3. Moreover, when the pointer 76 b of the scale76 c is set on a “larger area” side than the “standard” position of thescale 76 c, the focus area of the first focusing estimating part 2 islarger than the focus area of the second focusing estimating part 3.Note that a size ratio of the focus area is set variable correspondingto a rotational quantity of the knob 76 a on the basis of the “standardarea” position of the scale 76 c. Further, when the pointer 76 b is setto “AUTO” 76 d, the focus area of the first focusing estimating part 2is varied in accordance with a size of the object.

The focus area size inputting device 76 outputs, to a focus area settingdevice 77, a resistance value of the knob 76 a, i.e., a signalcorresponding to a position pointed by the pointer 76 b of the knob 76a. Note that a knob constructed of a slide type variable resistor and amulti-stage switch or an encoder may substitute for the knob 71 aconsisting of the rotary type variable resistor in FIG. 22. Further, anoperating portion may be displayed on the finder 79 of the video camera,and this operating portion may be selectable by a switch provided in adifferent position from the finder 79 or by a touch panel disposed onthe finder 79. Moreover, the “AUTO” switch may be separately provided,and the “AUTO” function may be switched ON and OFF by depressing theknob.

The focus area setting device 77 sets the focus area of the firstfocusing estimating part 2 on the basis of the signal transmitted fromthe focus area size inputting device 76. For instance, when the“standard area” is inputted to the focus area size inputting device 76,as shown in FIG. 23, the focus area of the first focusing estimatingpart 2 is set in substantially the same size and in the same position asthose of the focus area 111 of the second focusing estimating part 3.Further, when the “larger area” is inputted to the focus area sizeinputting device 76, the focus area of the focusing estimating part 2 isset to an area 113 b larger than the focus area 111 as well as insubstantially the same position as the focus area 111 of the secondfocusing estimating part 3. Furthermore, when the “smaller area” isinputted to the focus area size inputting device 76, the focus area ofthe focusing estimating part 2 is set to an area 113 a smaller than thefocus area 111 as well as in substantially the same position as thefocus area 111 of the second focusing estimating part 3.

Further, when the “AUTO” is inputted to the focus area size inputtingdevice 76, the focus area of the first focusing estimating part 2 is setin the following procedures. To start with, the focus area settingdevice 77, as shown in FIG. 24, obtains a distance from thephotographing optical system 1 to the object for every objectphotographed in each of the unit areas 111 a-111 i on the basis of animage deviation quantity detected in each of the unit areas 111 a-111 iof the focus area 111 of the second focusing estimating part 3. Next,the focus area setting device 77 detects the unit areas adjacent to eachother and having substantially the same distance from the photographingoptical system 1 to the object, from the unit areas 111 a-111 i. It canbe assumed that the identical object is photographed in the unit areasadjacent to each other and having substantially the same distance fromthe photographing optical system to the object. Hence, it can be judgedthat a size of the object corresponds to a region surrounded by theseunit areas. Next, the focus area setting device 77 sets an areaincluding the detected unit areas by way of the focus area of the firstfocusing estimating part 2. For example, referring to FIG. 24, when theunit areas 111 c, 111 d are detected, an area 114 a is set as the focusarea of the first focusing estimating part 2. Also, when the unit areas111 c-111 e are detected, an area 114 b is set as the focus area of thefirst focusing estimating part 2.

Moreover, the focus area setting device 77 issues a command to the firstfocusing estimating part 2 to create the first focusing estimated valuebased on the thus set focus area. This focus area setting device 77 isso constructed of, e.g., the CPU (Central Processing Unit), etc. as tobe integral with the focusing estimated value creating devices 23, 36and the focusing method selecting device 4.

The focus area display device 78, when the focusing method selectingdevice 4 selects the first focusing estimated value, displays the focusarea of the first focusing estimating part 2 on the finder 79 of thevideo camera, and, when selecting the second focusing estimated value,displays the focus area of the second focusing estimating part 3thereon. Incidentally, those areas may be displayed on a monitor screenor the like as well as on the finder 79 together.

In the fourth embodiment of the present invention, the size of the focusarea of the first focusing estimating part 2 may be made variable withrespect to the size of the focus area of the second focusing estimatingpart 3. Therefore, the focus area making use of advantages of the crestclimbing method and of the image deviation method, can be set.

For instance, when the focus area of the first focusing estimating part2 is set smaller than the focus area of the second focusing estimatingpart 3, a hitherto-undetectable minute object can be focused on in thesecond focusing estimating part 3. Further, the first estimating part 2takes a charge of correspondence to the minute object, and consequentlythe accuracy can be decreased by increasing the resolutions of the linesensors 34 a, 34 b of the second focusing estimating part 3. A rise inthe costs can be thereby restrained.

Moreover, in accordance with the fourth embodiment of the presentinvention, one of the focus areas of the first and second focusingestimating parts 2 and which area is selected by the focusing methodselecting device 4, is displayed on the finder 79, and hence thephotographer is able to always confirm the focus area.

Note that the focus area size inputting device 76 has been explained sofar as the one capable of inputting both of the manual adjustment andthe auto control in the fourth embodiment of the present invention, butthe present invention is not confined to this. For instance, asillustrated in FIG. 25, only two kinds of items “standard area” and“AUTO” with an omission of the manual adjustment may be switched over bya switch, or reversely, with an omission of “AUTO”, the setting is doneby only the manual knob. Also, as shown in FIG. 26, four sorts of items“standard area”, “large area”, “small area” and “AUTO” may be switchedover by the switch.

Further, as discussed in the first embodiment, some of even the imagedeviation type autofocus apparatuses have been developed so as to becapable of setting the plurality of portions within the photographicarea as the focus area. If the autofocus apparatus of this kind is usedfor the second focusing estimating part 3 in the fourth embodiment, asillustrated in FIG. 27, even the image deviation type apparatus iscapable of setting the focus area over the plurality of areas 115.Therefore, the focus area size inputting device 76 is set to “AUTO”,whereby the distance from the photographing optical system 1 to theobject can be obtained for every object photographed within the focusareas 115 on the basis of the image deviation quantity in each of thefocus areas 115. A size of the object can be thereby determined, andhence, the focus area of the first focusing estimating part 2 can be setcorresponding to the size of the object.

Note that when the autofocus apparatus in each of the first throughfourth embodiments is applied to the video camera, etc., it is a generalconstruction that a lens barrel incorporates the photographing opticalsystem 1 and the motor 5, and a camera body incorporates otherconstructive elements. The present invention is not, however, limited tothis construction.

Next, a fifth embodiment of the present invention will be discussed withreference to the drawings.

FIG. 28 is a schematic block diagram illustrating the autofocusapparatus in the fifth embodiment of the present invention. Note thatthe elements having the same functions as those in the first embodimentshown in FIG. 10 or the third embodiment shown in FIG. 15 are markedwith the like or corresponding numerals in the fifth embodiment of thepresent invention, and the detailed explanations thereof are omitted.

The autofocus apparatus in the fifth embodiment, as illustrated in FIG.28, includes a photographing optical system 1 a, the first focusingestimating part 2, the motor 5, the motor driving device 6, the objectdimension setting device 71, the object dimension calculating device 72,the focusing object controlling device 73, the focus adjusting lensencoder 74, the variable magnification lens encoder 75, and a distancemeasuring device 86. Herein the first focusing estimating part 2, themotor 5 and the motor driving device 6 are identical with those used inthe first embodiment. Further, the object dimension setting device 71,the object dimension calculating device 72, the focusing objectcontrolling device 73, the focus adjusting lens encoder 74, and thevariable magnification lens encoder 75 are identical with those employedin the third embodiment.

A different point of the photographing optical system 1 a from thephotographing optical system 1 used in the first embodiment is that theoptical element 15 for splitting the light beam is removed therefrom.

Others are the same as those in the photographing optical system 1. Thedistance measuring device 86 measures a distance from the photographingoptical system 1 a to the object that corresponds to the first focusingestimated value created by the first focusing estimating part 2. Adistance measuring method that can be considered may be a methodinvolving the use of infrared rays.

In accordance with the fifth embodiment of the present invention, a realdimension of the object can be measured by providing the distancemeasuring device 86 for measuring the distance from the photographingoptical system 1 a in the autofocus apparatus constructed to perform thefocusing by use of only the crest climbing method. Further, in thedistance measuring device 86, the accuracy for calculating the dimensionof the object may suffice, and there is no necessity for making ahigh-accuracy measurement. It is therefore feasible to perform theautofocus operation for only the object having substantially the samedimension as the dimension set by the object dimension setting device71, or executing the autofocus operation for only the object having adimension exclusive of the dimension set by the object dimension settingdevice 71. Accordingly, it is possible to prevent the focusing on anunexpected object and an object traversing in front of the objectconcerned.

The present invention is not confined to the respective embodimentsdiscussed above but may be modified in many ways within the gistthereof. Further, the autofocus apparatus in each of the embodimentstated above can be used for not only the video camera but also othercameras such as an electronic still camera, etc.

A sixth embodiment of the present invention will hereinafter bedescribed with reference to the drawings.

FIG. 29 is a schematic block diagram showing a TV camera in the sixthembodiment of the present invention. FIG. 30 is an explanatory flowchartshowing an autofocus operation of the TV camera illustrated in FIG. 29.

The TV camera in the sixth embodiment comprises, as shown in FIG. 29, acamera body 9 and a lens barrel 8 attached to the camera body 9. Thelens barrel 8 is so constructed as to be attachable to the camera body9, and the user is able to replace the lens barrel 8 to be attached tothe camera body according to the application.

The camera body 9 includes a first focusing estimating part 20, an AFprocessing circuit 40, and a connector 61. Further, the lens barrel 8includes a photographing optical system 10, a second focusing estimatingpart 30, a motor 50, a motor driving circuit 60, and a connector 62.Note that the connectors 61, 62 are, when the lens barrel 8 is attachedto the camera body 9, so constructed as to be electrically connected toeach other.

The photographing optical system 10 of the lens barrel 8 is constructedof four lens units such as a focus adjusting lens 11, a variablemagnification lens 12, a correcting lens 13 and an image forming lens14. This construction is typical of the lens barrel for the TV camera.In the photographing optical system 10 used in the sixth embodiment, abeam splitting element (e.g., a beam splitter) 45 for splitting lightbeams and a stop 16 are interposed in between the correcting lens 13 andthe image forming lens 14. Note that the optical element 45 is disposedanterior to the stop 16 so that the light beams can be transmitted tothe second focusing estimating part 30 irrespective of an aperturequantity of an aperture stop of the photographing optical system 10 inthe sixth embodiment.

The first focusing estimating part 20 estimates focusing by a so-calledcrest climbing type autofocus system. The first focusing estimating part20 includes, the imaging element 21 for picking up an image formed bythe image forming lens 14 of the photographing optical system 10 andconverting it into an electric signal, and the picture signal makingdevice 22 for generating a picture signal corresponding to the electricsignal transmitted from the imaging element 21. The first focusingestimating part 20 also includes the focusing estimated value creatingdevice 23 for creating an item of focusing data (termed also a firstfocusing estimated value) for focusing the image on the imaging element21 on the basis of the picture signal given from the picture signalmaking device 22. The focusing estimated value creating device 23 has alevel detecting portion 23 a for detecting a level of a proper frequencycomponent from the picture signal generated by the picture signal makingdevice 22, and an estimated value creating portion 23 b for creating thefirst focusing estimated value by examining the level detected by thelevel detecting portion 23 a.

Next, the first focusing estimated value created by the focusingestimated value creating device 23 will be explained. As described inthe prior art, the picture signal is, it can be assumed, formed bysynthesizing sine waves of a plurality of frequencies. Then, it isempirically known that a level of high frequency component of thepicture signal, as illustrated in FIG. 2, rises more steeply accordingas a degree of sharpness of the image formed on the imaging element 21increases, i.e., the focus adjusting lens 11 moves closer to a focusingpoint A, and this level reaches a peak when the image on the imagingelement 21 is focused on. Subsequently, the focusing estimated valuecreating device 23 selects a proper high frequency component inconsideration of an S/N ratio of the picture signal as well as of animaging performance of the photographing optical system 10, out of thepicture signal obtained by the picture signal making device 22. Then,the focusing estimated value creating device 23 creates a focusingestimated value by monitoring a level of this frequency component at apredetermined sampling interval. For example, when the level of theselected frequency component rises, it is estimated that the focusadjusting lens 11 is moving in such a direction as to approach afocusing point. Further, when the level of the selected frequencycomponent lowers, it is estimated that the focus adjusting lens 11 ismoving in such a direction as to get away from the focusing point. Then,when the level of the selected frequency component exists within apredetermined range (shown by, e.g., ΔV in FIG. 2) from the peak value,it is estimated that the image on the imaging element 21 is focused on.

The second focusing estimating part 30 estimates focusing by using anautofocus system known as the image deviation method. The secondfocusing estimating part 30 comprises the mirror 31 for reflecting thelight beam split by the beam splitting element 45, toward apredetermined direction, and the image forming lens 32 for forming lightbeams incident via the mirror 31 into a conjugate image. The secondfocusing estimating part 30 further comprises the image re-forminglenses 33 a, 33 b for forming some of the light beams image formed bythe image forming lens 32, again into images, the line sensors 34 a, 34b for respectively picking up the images formed by the image re-forminglenses 33 a, 33 b and converting them into electric signals, the imageprocessing device 35, and the focusing estimated value creating device36.

The image forming lens 32 is disposed so that the light beams incidentvia the mirror 31 are image-formed on the predetermined focal surface 37when the image on the imaging element 21 is focused on. The imagere-forming lenses 33 a, 33 b are disposed in positions substantiallysymmetric with respect to the optical axis of the image forming lens 32.The line sensors 34 a, 34 b are disposed in the positions substantiallysymmetric with respect to the optical axis of the image forming lens 32and on a predetermined focal surface of the image re-forming lenses 33a, 33 b corresponding to each other. The image processing device 35executes the image processing based on the electric signals transmittedrespectively from the line sensors 34 a, 34 b. The focusing estimatedvalue creating device 36 creates an item of data (also called a secondfocusing estimated value) for focusing the image formed on the imagingelement 21 on the basis of the signal transmitted from the imageprocessing device 35. The focusing estimated value creating device 36includes a positional deviation detecting portion 36 a for detecting animaging positional deviation (a deviating direction and a deviationquantity) between the image on the imaging element 34 a and the image onthe imaging element 34 b on the basis of the signal transmitted from theimage processing device 35, and an estimated value creating portion 36 bfor creating a second focusing estimated value based on the imagingpositional deviation detected by the positional deviation detectingportion 36 a.

Herein, the second focusing estimated value created by the focusingestimated value creating device 36 will be explained. FIGS. 31, 33 and35 are partially enlarged diagrams of the second focusing estimatingpart 30, showing the principle of the image deviation type autofocussystem. Herein, FIG. 31 illustrates a light path when in a focusedstate. FIGS. 33 and 35 illustrate optical paths when in a defocusedstate.

As illustrated in FIG. 31, the light beams passing through the imageforming lens 32 are focused upon the predetermined focal surface 37,some of the light beams are again image formed on the line sensors 34 a,34 b by the image re-forming lenses 33 a, 33 b. Herein, when focused onthe predetermined focal surface 37, the images picked up by the two linesensors 34 a, 34 b are formed in substantially coincident positions onthe line sensors as shown in FIG. 32. On the other hand, as shown inFIG. 33, when the light beams passing through the image forming lens 32are focused on anterior to the predetermined focal surface 37 (which isa so-called rear focus state), there must be a deviation between imagesD₁, D₂ picked up by the two line sensors 34 a, 34 b. Also, asillustrated in FIG. 35, when the light beams passing through the imageforming lens 32 are focused on posterior to the predetermined focalsurface 37 (which is a so-called a front focus state), there must be adeviation between in a direction opposite to the one in the rear focusstate between the images D₁, D₂ picked up by the two line sensors 34 a,34 b. Then, the focusing estimated value creating device 36 detects adeviation quantity and a deviating direction between the images D₁, D₂picked up by the line sensors 34 a, 34 b, and, based on the datathereof, creates a moving direction and a moving quantity (a secondfocusing estimated value) of the focus adjusting lens 11, which areneeded for focusing the image on the predetermined focal surface 37,i.e., the image on the imaging element 21. Note that the second focusingestimated value is created at the interval of a predetermined time inconsideration of a processing speed, etc. of the image processing device35.

Thus, in the image deviation type autofocus system, the focusing iseffected based on the deviating direction and the deviation quantitybetween the positions of the images picked up by the pair of linesensors. This is the reason why it is called the image deviation method.According to the image deviation type autofocus system, therequired-for-focusing moving direction and moving quantity of the focusadjusting lens are directed calculated based on the deviating directionand the deviation quantity between the positions of the images picked upby the pair of line sensors, and therefore the focusing can be quicklycarried out. For this reason, the apparatus is employed as an autofocusapparatus mainly for a still camera.

The AF processing circuit 40 of the camera body 9 has motor drivingsignal generating portions 41, 42, and a selecting portion 43. The motordriving signal generating portion 41 refers to the first focusingestimated value created by the first focusing estimating part 20, andthus generates a drive signal of the motor 50. For instance, if thefirst focusing estimated value represents such an estimation that thefocus adjusting lens 11 is moving in such a direction as to approach thefocusing point, the drive signal is generated to make a rotatingdirection of the motor 50 remain unchanged. Further, if the firstfocusing estimated value represents such an estimation that the focusadjusting lens 11 is moving in such a direction as get away from thefocusing point, the drive signal is generated to reverse the rotatingdirection of the motor 50. The motor driving signal generating portion42 refers to the second focusing estimated value created by the secondfocusing estimating part 30 and transmitted via the connectors 61, 62,and thus generates the drive signal to move the focus adjusting lens 11in the moving direction with the moving quantity, which are indicated bythe estimated value concerned. The selecting portion 43 selects at leastone of the drive signal generated by the motor driving signal generatingportion 41 and the drive signal generated by the motor driving signalgenerating portion 42. In the sixth embodiment, referring to the secondfocusing estimated value, if the required-for-focusing moving quantityof the focus adjusting lens 11 is larger than a threshold value, thedrive signal generated by the motor driving signal generating portion42, is selected. Whereas if smaller than the threshold value, the drivesignal generated by the motor driving signal generating portion 41, isselected. Note that this threshold value may be arbitrarily set by thephotographer or the like with inputting from outside or by some othermethods. The thus selected drive signals are transmitted via theconnectors 61, 62 to the motor driving circuit 60.

The motor driving circuit 60 of the lens barrel 8 drives the motor 50based on the drive signal selected, by the selecting portion 43. Thefocus adjusting lens 11 is thereby moved forward and backward in theoptical-axis direction of the photographing optical system 10.

Note that the picture signal making device 22, the focusing estimatedvalue creating device 23 and the AF processing circuit 40 of the camerabody 9 are integrally constructed of, e.g., the CPU (Central ProcessingUnit), etc. Similarly, the image processing device 35 and the focusingestimated value creating device 36 of the lens barrel 8 are alsointegrally constructed of the CPU (Central Processing Unit), etc.

Next, the autofocus operation of the TV camera in the sixth embodimentwill be explained with reference to FIG. 30.

At the first onset, upon an incidence of the light beams emerging fromthe object on the photographing optical system 10, the first focusingestimating part 20 creates the first focusing estimated value based onthe light beams obtained through the image forming lens 14 in thephotographing optical system 10. Further, the second focusing estimatingpart 30 creates the second focusing estimated value based on the lightbeam split by the beam splitting element 45 in the photographing opticalsystem 10 (step 201).

Next, the selecting portion 43 of the AF processing circuit 40 judgeswhether or not the first focusing estimated value gives an indication ofbeing focused (step 202). If the first focusing estimated valueindicates a purport of being focused, a flow of processing shown in FIG.30 comes to an end. Whereas if not, the processing proceeds to step 203.

In step 203, the selecting portion 43 of the AF processing circuit 40refers to the second focusing estimated value, and judges whether or notthe required-for-focusing moving quantity of the focus adjusting lens 11is under the threshold value. If the required-for-focusing movingquantity of the focus adjusting lens 11 is under the threshold value,the drive signal generated by the motor drive signal generating portion41 is selected based on the first focusing estimated value (step 204).While on the other hand, if over the threshold value, the drive signalgenerated by the motor driving signal generating portion 42 is selectedbased on the second focusing estimated value (step 205).

Next, the motor driving device 60 drives the motor on the basis of thedrive signal selected by the selecting portion 43 (step 206).

The processing flow shown in FIG. 30 is repeatedly executed till thefirst focusing estimated value comes to have a content of being focused.The image on the imaging element 21 is thereby focused on.

In the sixth embodiment, the first focusing estimated value is createdby the first focusing estimating part 20 involving the use of the crestclimbing type autofocus system capable of focalizing with a highprecision. Then, the second focusing estimated value is created by thesecond focusing estimating part 30 involving the use of the imagedeviation type autofocus system capable of quick focalizing. Further,the AF processing circuit 40, if the second focusing estimated valuecreated by the second focusing estimating part 30 is over the thresholdvalue, selects the second focusing estimated value, and, whereas ifunder the threshold value, selects the first focusing estimated value.Then, the drive signal for the motor 50 is generated based on the thusselected focusing estimated value. With this processing, to begin with,the image on the imaging element 21 is roughly focused on by making useof the second focusing estimated value. Thereafter, the image on theimaging element 21 is finely focused on by use of the first focusingestimated value. Accordingly, in the sixth embodiment, it is feasible tofocus the image on the imaging element 21 quickly with the highaccuracy. Further, the high precision is not demanded of the secondfocusing estimating part 30 employing the image deviation method, andconsequently an increase in costs can be restrained.

Moreover, in the sixth embodiment, the first focusing estimating part 20is provided on the side of the camera body 1, while the second focusingestimating part 20 is provided on the side of the lens barrel. Herein,the first focusing estimating part 20 creates the focusing estimatedvalue for focusing the image on the imaging element 21 on the basis ofthe image on the imaging element 21, and can be therefore used in commonirrespective of the structure of the photographing optical system 10. Onthe other hand, the second focusing estimating part 30 creates thefocusing estimated value for focusing the image on the imaging element21 by use of the image to be formed in a different position from thesurface on the imaging element 21, and might therefore need to changethe structure (especially, a layout of the image forming lens 32 and theimage re-forming lenses 33 a, 33 b) if the structure of thephotographing optical system 10 varies. As discussed above, inaccordance with the sixth embodiment, the camera body 1 is provided withthe first focusing estimating part 20 capable of being used in common,regardless of the structure of the photographing optical system 10,i.e., even when replacing the lens barrel. Then, the lens barrel 2 isprovided with the second focusing estimating part 30 peculiar to thephotographing optical system 10, thereby making it possible to preventthe rise in costs for the lens barrel as well as to downsize the lensbarrel.

Moreover, in the sixth embodiment, the focal length of the opticalsystem for forming the images for detecting the image deviation on theline sensors 34 a, 34 b, is a synthetic focal length of the focusadjusting lens 11, the variable magnification lens 12, the correctinglens 13 and the image forming lens 32. On the other hand, the focallength of the optical system for forming the image for the picturesignal on the imaging element 21, is a synthetic focal length of thefocus adjusting lens 11, the variable magnification lens 12, thecorrecting lens 13 and the image forming lens 14. Accordingly, the focallengths of the optical system for forming the images for detecting theimage deviation and of the optical system for forming the image for thepicture signal, are varied by changing the configurations of the imageforming lenses 14, 32. Videlicet, the sizes of the images formed by therespective optical systems can be varied. For example, the image forminglens 32 is constructed to enlarge the image for detecting the imagedeviation by elongating the focal length of the optical system forforming the images for detecting the image deviation, thereby obtaininga finer pixel pitch of the line sensors 34 a, 34 b relative to the aboveimage. Hence, it is feasible to focus on even a minute object. Further,for instance, the image forming lens 32 is constructed to diminish theimage for detecting the image deviation by shortening the focal lengthof the optical system for forming the image for detecting the imagedeviation, whereby a size of this image decreases relatively to the linesensors 34 a, 34 b. Therefore, a detectable image deviation quantityincreases. Such being the case, even when the focus adjusting lens ispositioned far from the focusing point (a so-called largely defocusedstate), the focusing point can be quickly detected. Further, the lensbarrel can be downsized.

Note that the selecting portion 43 of the AF processing circuit 40 ispermitted to judge whether or not the lens barrel 8 should include thesecond focusing estimating part. This judgement may be made based onwhether or not the signal indicating the second focusing estimated valueis transmitted from the lens barrel via the connectors 61, 62. Also, theconnector 62 of the lens barrel 8 may be provided with a contact pointfor distinguishing an existence or non-existence of the second focusingestimating part, and the selecting portion 43 may make a judgement aboutthis contact point. If the lens barrel 2 does not include the secondfocusing estimating part, the drive signal generated by the drivingsignal generating portion 41 is selected based on the first focusingestimated value, whereby the lens barrel corresponding to thehitherto-used crest climbing type autofocus system can be also employed.Moreover, if the lens barrel 8 has the second focusing estimating part,the focusing data created by the second focusing estimating partincorporated into the lens barrel 8 can be effectively availed.

Next, a seventh embodiment of the present invention will be explainedwith reference to the drawings.

FIG. 37 is a schematic block diagram of the TV camera in the seventhembodiment of the present invention. Note that the elements having thesame functions as those in the sixth embodiment shown in FIG. 29 aremarked with the like or corresponding numerals in the seventh embodimentof the present invention, and the detailed explanations thereof areomitted.

A different point of the TV camera in the seventh embodiment from thatin the sixth embodiment shown in FIG. 29 is that the camera body 1 a is,as illustrated in FIG. 37, provided with an AF processing circuit 40 ainstead of the AF processing circuit 40, and that the lens barrel 8 isprovided with an AF processing circuit 40 b. The AF processing circuit40 a includes the motor driving signal generating portion 41. The AFprocessing circuit 40 b includes the motor driving signal generatingportion 42 and the selecting portion 43.

In the seventh embodiment, the lens barrel 8 incorporates the AFprocessing circuit 40 b consisting of the motor driving signalgenerating portion 42 for generating the motor driving signal on thebasis of the second focusing estimated value, and the selecting portion43 for selecting at least one of the drive signal generated by the motordriving signal generating portion 41 and the drive signal generated bythe motor driving signal generating portion 42. With this construction,there can be used the camera body 9 a corresponding to thehitherto-employed crest climbing type autofocus system as illustrated inFIG. 9. That is, in accordance with the seventh embodiment, even whenusing the camera body corresponding to the hitherto-used crest climbingtype autofocus system, the image on the imaging element 21 can befocused on quickly with the high precision. Other effects are the sameas those in the first embodiment.

Note that the selecting portion 43 of the AF processing circuit 40 b ispermitted to judge whether or not the camera body 9 a includes the firstfocusing estimating part. This judgement may be made based on whether ornot the motor driving signal is transmitted from the camera body 9 a viathe connectors 61, 62. Further, the connector 61 of the camera body maybe provided with a contact point for distinguishing an existence ornon-existence of the first focusing estimating part, and the selectingportion 43 may make a judgement about this contact point. If the camerabody 9 a does not have the first focusing estimating part, the drivesignal generated by the driving signal generating portion 42 is selectedbased on the second focusing estimated value, whereby the autofocusfunction can be actualized even when the camera body not correspondingto the autofocus is attached to the lens barrel 8 a. Moreover, in thecase of the lens barrel 8 a being fitted with the camera bodycorresponding to the autofocus, the autofocus function of the camerabody can be effectively availed.

Next, an eighth embodiment of the present invention will be describedwith reference to the drawings.

FIG. 38 is a schematic block diagram of the TV camera in the eighthembodiment of the present invention. Note that the elements having thesame functions as those in the sixth embodiment shown in FIG. 29 aremarked with the like or corresponding numerals in the eighth embodiment,and the detailed explanations thereof are omitted.

A different point of the TV camera in the eighth embodiment from that inthe sixth embodiment shown in FIG. 29 is that the lens barrel 8 b is, asillustrated in FIG. 38, provided with the AF processing circuit 40 andthe focusing estimated value creating device 23 of the first focusingestimating part.

In the eighth embodiment, the lens barrel 8 b incorporates the focusingestimated value creating device 23, the second focusing estimating part30 and the Af processing circuit 40. With this construction, even whenthe camera body not corresponding to the autofocus is attached to thelens barrel 8 b, the image on the imaging element 21 can be focused onquickly with the high accuracy by using the two sorts of image deviationtype and crest climbing type autofocus systems.

Note that the picture signal making device 22 may be disposed on theside of the lens barrel 8 b in the eighth embodiment.

Next, a ninth embodiment of the present invention will be described withreference to the drawings.

FIG. 39 is a schematic block diagram of the TV camera in the ninthembodiment of the present invention. Note that the elements having thesame functions as those in the sixth embodiment shown in FIG. 29 aremarked with the like or corresponding numerals in the ninth embodiment,and the detailed explanations thereof are omitted.

The TV camera in the ninth embodiment includes, as illustrated in FIG.39, a camera body 9 c and a lens barrel 8 c attached to the camera body9 c. The camera body 9 c has the imaging element 21, the picture signalmaking device 22 and the connector 61. Further, the lens barrel 8 c hasthe photographing optical system 10, the focusing estimated valuecreating device 23, the processing circuit 40 c, the motor 50, the motordriving circuit 60 and the connector 62. The AF processing circuit 40 chas the drive signal generating portion 41 for generating the drivesignal for the motor 50 by referring to the focusing estimated valuecreated by the focusing estimated value creating device 23.

In accordance with the ninth embodiment, the lens barrel 8 cincorporates the crest climbing type autofocus function to create thefocusing estimated value on the basis of the image on the imagingelement 21 in the camera body 9 c. With this construction, even when thecamera body not corresponding to the autofocus is attached to the lensbarrel, the image on the imaging element 21 can be focused on with thehigh precision by employing the crest climbing type autofocus system.

Next, a tenth embodiment of the present invention will be discussed withreference to the drawings.

FIG. 40 is a schematic diagram of the TV camera in the tenth embodimentof the present invention. Note that the elements having the samefunctions as those in the sixth embodiment shown in FIG. 29 are markedwith the like or corresponding numerals in the tenth embodiment, and thedetailed explanations thereof are omitted.

The TV camera in the tenth embodiment includes, as illustrated in FIG.40, a camera body 9 d and a lens barrel 8 d attached to the camera body9 d. The camera body 9 d has the imaging element 21. Further, the lensbarrel 8 d has the photographing optical system 10, the second focusingestimating part 30, an Af processing circuit 40 d, the motor 50, and themotor driving circuit 60. The AF processing circuit 40 d has the drivesignal generating portion 42 for generating the drive signal for themotor 50 by referring to the focusing estimated value created by thesecond focusing estimating part 30.

In accordance with the tenth embodiment, the lens barrel 8 dincorporates the image deviation type autofocus function to directlycalculate the required-for-focusing moving direction and moving quantityof the focus adjusting lens 11. With this construction, even when thecamera body not corresponding to the autofocus is attached to the lensbarrel, the image on the imaging element 21 can be focused on quickly byemploying the image deviation type autofocus system.

The present invention is not limited to the respective embodimentdiscussed above but may be modified in a variety of forms within thescope of the gist thereof. for instance, the focusing estimated valuecreating device 23 for creating the focusing estimated value (the firstfocusing estimated value) based on the crest climbing method has beenexplained so far by way of the one for creating the first focusingestimated value on the basis of the picture signal generated by thepicture signal making device 22. The first focusing estimated value maybe, however, created based on the electric signal outputted from theimaging element 21. Also, a predetermined process for creating the firstfocusing estimated value is executed upon the electric signal outputtedfrom the imaging element 21, and the first focusing estimated value maybe created based on the signal undergoing this process.

Further, the AF processing circuit 43 has been described so far by wayof the one for selecting at least one of the drive signal generated bythe motor driving signal generating portion 41 and the drive signalgenerated by the motor drive signal generating portion 42. The presentinvention is not, however, confined to this. The selecting portion maybe constructed to select at least one of the first and second focusingestimated values. In this case, the motor driving signal generated basedon the thus selected focusing estimated value may be transmitted to themotor driving circuit 60.

Further, the present invention may be applied to not only the TV camerabut also other video cameras and electronic still cameras, etc.

An eleventh embodiment of the present invention will hereinafter bedescribed with reference to the drawings.

FIG. 41 is a schematic block diagram showing the autofocus apparatus inthe eleventh embodiment of the present invention. FIG. 42 is anexplanatory flowchart showing an operation of the autofocus apparatusillustrated in FIG. 41. FIG. 43 is an explanatory flowchart showing anoperation of the first focusing estimating part shown in FIG. 41. FIG.44 is an explanatory flowchart showing an operation of the secondfocusing estimating part depicted in FIG. 41. FIG. 45 is an explanatoryflowchart showing an operation of a defocus storage device shown in FIG.41.

The autofocus apparatus in the eleventh embodiment includes, asillustrated in FIG. 41, the photographing optical system 1, the firstfocusing estimating part 2, the second focusing estimating part 3, thefocusing method selecting device 4, the motor 5, the motor drivingdevice 6, and a defocus storage device 7. Note that when the autofocusapparatus in the eleventh embodiment is applied to the video camera,etc., it is a general construction that the lens barrel incorporates thephotographing optical system 1 and the motor 5, while the camera bodyincorporates other constructive elements. The present invention is not,however, limited to this construction.

The photographing optical system 1 is constructed of four lens unitssuch as the focus adjusting lens 11, the variable magnification lens 12,the correcting lens 13 and the image forming lens 14. This constructionis typical of the lens barrel for the TV camera. In the photographingoptical system 1 used in the eleventh embodiment, the optical element(e.g., the beam splitter) 45 for splitting light beams and the stop 16are interposed in between the correcting lens 13 and the image forminglens 14. Note that the optical element 45 is disposed anterior to thestop 16 so that the light beams can be transmitted to the secondfocusing estimating part 3 irrespective of an aperture quantity of anaperture stop of the photographing optical system 1 in the eleventhembodiment.

The first focusing estimating part 2 estimates the focusing by theso-called crest climbing method. The first focusing estimating part 2includes the imaging element 21 for picking up an image formed by theimage forming lens 14 of the photographing optical system 1 andconverting it into an electric signal, and a picture signal makingdevice 22 for generating a picture signal corresponding to the electricsignal transmitted from the imaging element 21. The first focusingestimating part 2 also includes the focusing estimated value creatingdevice 23 for creating the data (the first focusing estimated value) forfocusing the image on the imaging element 21 on the basis of the picturesignal given from the picture signal making device 22. The focusingestimated value creating device 23 has the level detecting portion 23 afor detecting a level of a proper frequency component from the picturesignal generated by the picture signal making device 22, and theestimated value creating portion 23 b for creating the first focusingestimated value by examining the level detected by the level detectingportion 23 a. Note that the electric signal outputted from the imagingelement 21 is used for generating the picture signal of the video cameraas illustrated in FIG. 41.

The second focusing estimating part 3 estimates the focusing by theso-called image deviation method. The second focusing estimating part 3comprises the mirror 31 for reflecting the light beam split by theoptical element 45, toward a predetermined direction, and the imageforming lens 32 for forming the light beams incident via the mirror 31into a conjugate image. The second focusing estimating part 3 furthercomprises the image re-forming lenses 33 a, 33 b for forming some of thelight beams image formed by the image forming lens 32, again intoimages, the line sensors 34 a, 34 b for respectively picking up theimages formed by the image re-forming lenses 33 a, 33 b and convertingthem into electric signals, the image processing device 35, and thefocusing estimated value creating device 36.

The image re-forming lenses 33 a, 33 b are disposed in positionssubstantially symmetric with respect to the optical axis of the imageforming lens 32. More specifically, the image reforming lenses 33 a, 33b are so disposed as to individually re-form the images of the lightbeams passing through portions having different pupils in the opticalsystem consisting of the focus adjusting lens 11, the variablemagnification lens 12, the correcting lens 13 and the image forming lens32, among the light beams for forming the image formed by the imageforming lens 32. The line sensors 34 a, 34 b are disposed in thepositions substantially symmetric with respect to the optical axis ofthe image forming lens 32 and on a predetermined focal surface of theimage re-forming lenses 33 a, 33 b corresponding to each other. Theimage processing device 35 executes the image processing based on theelectric signals transmitted respectively from the line sensors 34 a, 34b. The focusing estimated value creating device 36 creates the data(hereinafter termed also the second focusing estimated value) forfocusing the image on the imaging element 21 on the basis of the signaltransmitted from the image processing device 35. The focusing estimatedvalue creating device 36 includes the positional deviation detectingportion 36 a for detecting an imaging positional deviation (a deviatingdirection and a deviation quantity) between the image on the imagingelement 34 a and the image on the imaging element 34 b on the basis ofthe signal transmitted from the image processing device 35. The focusingestimated value creating device 36 also comprises a correcting portion36 b for correcting the imaging positional deviation detected by thepositional deviation detecting portion 36 a, with a correction valuestored in a defocus quantity storage device 7 which will be mentionedalter on, and an estimated value creating portion 36 c for creating thesecond focusing estimated value based on the imaging positionaldeviation corrected by the correcting portion 36 b.

The defocus quantity storage device 7 stores, as a correction value, adefocus quantity between the image on the predetermined focal surface 37and the image on the imaging element 21. Incidentally, if a non-volatilememory is used as a storage medium of the defocus storage device 7, thedefocus quantity can be retained even in such a case that the powersupply of the apparatus in the eleventh embodiment is, after beingswitched OFF, again switched ON. Hence, the image positional deviationdetected by the positional deviation detecting portion 36 a can beimmediately corrected with the relevant defocus quantity.

The focusing method selecting device 4 selects at least one of the firstfocusing estimated value created by the first focusing estimating part 2and the second focusing estimated value created by the second focusingestimating part 3. In accordance with the eleventh embodiment, referringfirst to the second focusing estimated value, if the defocus quantity orthe required-for-focusing moving quantity of the focus adjusting lens 11is larger than a threshold value, the second focusing estimated value isset to be selected. Whereas if smaller than the threshold value, thefirst focusing estimated value is set to be selected. Note that thisthreshold value may also be set arbitrarily by the photographer and soforth through inputting from outside.

The motor driving device 6 drives the motor 5 on the basis of thefocusing estimated value selected by the focusing method selectingdevice 4. Based on a command given from the motor driving device 6, themotor 5 moves the focus adjusting lens 11 forward and backward in theoptical-axis direction of the photographing optical system 1.

Incidentally, the focusing estimated value creating devices 23, 36, thefocusing method selecting device 4 and the defocus quantity storagedevice 7 are integrally constructed of, e.g., the CPU (CentralProcessing Unit), etc.

Next, an operation of the autofocus apparatus as a whole in the eleventhembodiment will be described referring to FIG. 42.

To start with, upon an incidence of the light beams upon thephotographing optical system 1 from the object, the first focusingestimating part 2 creates the first focusing estimated value on thebasis of the light beams obtained via the image forming lens 14 in thephotographing optical system 1. Further, the second focusing estimatingpart 3 creates the second focusing estimated value based on the lightbeams split by the optical element 45 in the photographing opticalsystem 1 (step 251).

Next, the focusing method selecting device 4 judges whether or not thefirst focusing estimated value gives an indication of being focused(step 252). If the first focusing estimated value indicates a purport ofbeing focused, a flow of processing shown in FIG. 42 comes to an end.Whereas if not, the processing proceeds to step 253.

In step 253, the focusing method selecting device 4 refers to the secondfocusing estimated value, and judges whether or not the defocus quantityor the required-for-focusing moving quantity of the focus adjusting lens11 is under the threshold value. If the required-for-focusing movingquantity of the focus adjusting lens 11 is under the threshold value,the first focusing estimated value created by the first focusingestimating part 2 is selected (step 254). Whereas if above the thresholdvalue, the second focusing estimated value selected by the secondfocusing estimating part 3 is selected (step 255).

Next, the motor driving device 6 drives the motor on the basis of thefocusing estimated value selected by the focusing method selectingdevice 4 (step 256). When the second focusing estimated value isselected by the focusing method selecting device 4, the motor drivingdevice 6 drives the motor 5 so that the focus adjusting lens 11 is movedin the moving direction by the moving quantity, which are indicated bythe selected second focusing estimated value. Further, when the firstfocusing estimated value is selected by the focusing method selectingdevice 4, it is estimated that the focus adjusting lens 11 is moving insuch a direction as to approach a focusing point. At this time, themotor 5 is driven to make the rotating direction thereof remainunchanged. Moreover, when it is estimated that the focus adjusting lens11 is moving in such a direction as to get away from the focusing point,the motor 5 is driven to reverse the rotating direction thereof.

The processing flow shown in FIG. 42 is repeatedly executed till thefirst focusing estimated value comes to have a content of being focused.The image on the imaging element 21 is thereby focused on.

Subsequently, an operation of the first focusing estimating part 2 inthe eleventh embodiment will be explained with reference to FIG. 43.

At first, the picture signal making device 22 converts the image formedon the imaging element 21 through the photographing optical system 1into a picture signal (step 301). As described in the prior art, thepicture signal is, it can be assumed, formed by synthesizing sine wavesof a plurality of frequencies. Then, it is well known that a level ofhigh frequency component of the picture signal, as illustrated in FIG.47, rises more steeply according to a degree of sharpness of the imageformed on the imaging element 21 increases, i.e., the focus adjustinglens 11 moves closer to a focusing point A, and this level reaches apeak when the image on the imaging element 21 is focused on.Subsequently, the focusing estimated value creating device 23 causes alevel detecting portion 23 a to detect a proper high frequency componentlevel at a predetermined sampling interval in consideration of an S/Nratio of the picture signal as well as of an imaging performance of thephotographing optical system 1, out of the picture signal obtained bythe picture signal making device 22 (step 302). Then, the focusingestimated value creating device 23 creates the focusing estimated valueby monitoring a level of this frequency component (step 303). Forexample, when the level of the selected frequency component rises, it isestimated that the focus adjusting lens 11 is moving in such a directionas to approach a focusing point. Further, when the level of the selectedfrequency component lowers, it is estimated that the focus adjustinglens 11 is moving in such a direction as to get away from the focusingpoint. Then, when the level of the selected frequency component existswithin a predetermined range (shown by, e.g., ΔV in FIG. 51) from thepeak value, it is estimated that the image on the imaging element 21 isfocused on.

Note that the processing flow shown in FIG. 43 is repeatedly executed ata predetermined time interval taking a processing speed, etc. in thepicture signal creating device 22 into consideration.

Next, an operation of the second focusing estimating part 3 in theeleventh embodiment will be explained with reference to FIG. 44.

To start with, the positional deviation detecting portion 36 a detects adeviating direction and a deviation quantity between the images pickedup by the line sensors 34 a, 34 b on the basis of the signalstransmitted from the image processing device 35 (step 401). As stated inthe prior art, when the light beams traveling through the image forminglens 32 are focused on the predetermined focal surface 37, some of thelight beams are again formed on the line sensors 34 a, 34 b by the imagere-forming lenses 33 a, 33 b. Hence, if focused on the predeterminedfocal surface 37, the images picked up by the two line sensors 33 a, 33b are formed in substantially coincident positions on the line sensors.On the other hand, when the light beams passing through the imageforming lens 32 are focused on anterior to the predetermined focalsurface 37 (which is the so-called rear focus state), there must be adeviation between the images picked up by the two line sensors 34 a, 34b. Also, when the light beams passing through the image forming lens 32are focused on posterior to the predetermined focal surface 37 (which isthe so-called front focus state), there must be a deviation in adirection opposite to the one in the rear focus state between the imagespicked up by the two line sensors 34 a, 34 b. Based on the deviatingdirection and deviation quantity between the images picked by the linesensors 34 a, 34 b, it can be therefore estimated how far the image onthe predetermined focal surface 37 exists away from the focusing point.

Next, the correcting portion 36 b corrects the image positionaldeviation detected by the positional deviation detecting portion 36 a,with the correction value stored in the defocus storage device 7 (step402). Incidentally, the following is an elucidation of the reason whythe image positional deviation detected by the positional deviationdetecting portion 36 a is corrected with the correction value stored inthe defocus storage device 7.

If the predetermined focal surface 37 and the imaging element 21 of thefirst focusing estimating part 2 are coincident with each other in termsof their optical positions, viz., if the image on the imaging element 21is focused on when the image on the predetermined focal surface 37 isfocused on, there can be directly made an estimation as to whether ornot the image on the imaging element 21 is focused on in accordance withthe image deviating direction and quantity that are detected by thepositional deviation detecting portion 36 a. However, if the opticalpositions of the predetermined focal surface 37 and of the imagingelement 21 deviate from each other, and if the predetermined focalsurface 37 and the imaging element 21 deviate in terms of their opticalpositions due to, e.g., a tracking adjustment, the image on the imagingelement 21 is not focused on when the image on the predetermined focalsurface 37 is focused on. Therefore, the estimation as to whether or notthe image on the imaging element 21 is focused on is made based on theimage deviating direction and quantity that are detected by thepositional deviation detecting portion 36 a, the focusing accuracydeclines. This being the case, the correcting portion 36 b corrects theimage positional deviation detected by the positional deviationdetecting portion 36 a, with the correction value stored in the defocusstorage device 7.

Next, the estimated value creating portion 36 c creates the secondfocusing estimated value indicating a moving direction and a movingquantity of the focus adjusting lens 11, which are needed for focusingthe image on the imaging element 21, on the basis of the positionaldeviating direction and quantity that are corrected by the correctingportion 36 b (step 403).

Note that the processing flow shown in FIG. 44 is repeatedly executed ata predetermined time interval in consideration of the processing speed,etc. in the image processing device 35.

Next, an operation of the defocus storage device 7 in the eleventhembodiment will be explained with reference to FIG. 46.

To begin with, in step 501, there is judged whether or not the firstfocusing estimated value created by the focusing estimated valuecreating device 23 indicates the purport that the image on the imagingelement 21 is focused on. If the first focusing estimated valueindicates this purport, the processing proceeds to step 502. Whereas ifnot, there must be waited till the first focusing estimated valueindicates that purport. Stored as a correction value in step 502 are thedeviating direction and deviation quantity between the images picked upby the line sensors 34 a, 34 b that are detected by the positionaldeviation detecting portion 36 a, i.e., a defocus quantity between theimage on the predetermined focal surface 37 and the image on the imagingelement 21 of the focusing estimating part 2.

Note that the processing flow shown in FIG. 45 may be executed accordingto a command from the user or the like. For example, when the command ofthe user is inputted to a predetermined button, a slide switch and soon, the processing flow shown in FIG. 45 may be executed. With thisoperation, when under a photographic condition enough to ensure adetection accuracy of the level detecting portion 23 a and of thepositional deviation detecting portion 36 a, the user switches ON thepredetermined button or slide switch, thereby making it possible todetect the defocus quantity with a high precision between the image onthe predetermined focal surface 37 and the image on the imaging element21. The processing flow shown in FIG. 45 may also be repeatedly executedduring the operation of the apparatus in the eleventh embodiment. Aplurality of correction values may be thereby obtained, and, from theseplurality of correction values, the defocus quantity between the imageon the predetermined focal surface 37 and the image on the imagingelement value can be enhanced. Moreover, the user performs the trackingadjustment or the like, and, even if the defocus quantity between theimage on the predetermined focal surface 37 and the image on the imagingelement 21 changes, a new defocus quantity can be automatically stored.

In accordance with the eleventh embodiment, the first focusingestimating part 2 creates the first focusing estimated value by use ofthe so-called crest climbing method, while the second focusingestimating part 3 creates the second focusing estimated value byemploying the so-called image deviation method. Further, the focusingmethod selecting device 4 selects the second focusing estimated valuewhen the second focusing estimated value created by the second focusingestimating part 3 is above the threshold value, and selects the firstfocusing estimated value when under the threshold value. Then, the motordriving device 6, based on the focusing estimated value selected by thefocusing method selecting device 4, drives the motor 5 to move the focusadjusting lens 11. With this operation, to begin with, the image on theimaging element 21 is roughly focused on by use of the second focusingestimated value, and thereafter the image on the imaging element 21 isfinely focused on by use of the first focusing estimated value.Accordingly, in the imaging element 21 can be focused on quickly with ahigh accuracy. Further, the high accuracy is not required of the secondfocusing estimating part 3 using the image deviation method, and hencethe costs can be restrained from rising.

Moreover, in the eleventh embodiment, the defocus storage device 7 isstored with the defocus quantity as the correction value between theimage on the predetermined focal surface 37 and the image on the imagingelement 21, and the imaging positional deviation detected by thepositional deviation detecting portion 36 a is corrected with therelevant correction value. The second focusing estimated value iscreated based on the thus corrected imaging positional deviation betweenthe images. Therefore, even if the deviation between the opticalpositions of the predetermined focal surface 37 and of the imagingelement 21 is caused due to, e.g., the tracking adjustment with theresult that the image on the imaging element 21 is not focused on whenthe image on the predetermined focal surface 37 is focused on, thefocusing accuracy of the second focusing estimated value can beprevented from declining.

Note that the image on the imaging element 21 is focused on by use ofthe first focusing estimated value in the end in accordance with theeleventh embodiment, second focusing estimated value declines, the finalfocusing accuracy of the image on the imaging element 21 does notchange. If the focusing accuracy of the second focusing estimated valuedeclines, however, a time of focusing operation involving the use of thefirst focusing estimated value created by the first focusing estimatingpart 2 elongates correspondingly. As a result, a time needed forfocusing the image on the imaging element 21 elongates. In this respect,according to the eleventh embodiment, as discussed above, the focusingaccuracy of the second focusing estimated value can be prevented fromdeclining, and therefore, even if there might be caused the deviationbetween the optical positions of the predetermined focal surface 37 andthe imaging element 21 due to the tracking adjustment, etc., the imageon the imaging element 21 can be focused on quickly with the highprecision.

Furthermore, in the eleventh embodiment, a focal length of the opticalsystem for forming the images for detecting the image deviation on theline sensors 34 a, 34 b, is a synthetic focal length of the focusadjusting lens 11, the variable magnification lens 12, the correctinglens 13 and the image forming lens 32. On the other hand, a focal lengthof the optical system for forming the image for the picture signal onthe focus adjusting lens 11, the variable magnification lens 12, thecorrecting lens 13 and the image forming lens 14. Therefore, the focallengths of the optical system for forming the images for detecting theimage deviation and of the optical system for forming the image for thepicture signal, are varied by changing the configurations of the imageforming lenses 14, 32, videlicet, the sizes of the images formed by therespective optical systems can be varied. For instance, the imageforming lens 32 is constructed to enlarge the images for detecting theimage deviation by increasing the focal length of the optical system forforming the images for detecting the image deviation, whereby the pixelpitches of the line sensors 34 a, 34 b become finer relatively to theabove images. Hence, it is feasible to focus even a minute object.Further, for example, the image forming lens 32 is constructed todiminish the images for detecting the image deviation by shortening thefocal length of the optical system for forming the images for detectingthe image deviation, whereby the sizes of these images become smallerrelatively to the line sensors 34 a, 34 b. Therefore, it is possible todetect a larger quantity of image deviation. Even if the focus adjustinglens is positioned far from the focusing point (which is the so-calledlargely defocused state), the focusing point can be downsized.

The present invention is not confined to the embodiment discussed abovebut may be modified in a variety of forms within the scope of the gistthereof. For example, in the eleventh embodiment, the defocus storagedevice 7 has been thus far explained as the one for storing thepositional deviation between the images on the line sensors 34 a, 34 bthat is detected by the positional deviation detecting portion 36 a asthe defocus quantity between the image on the predetermined focalsurface 37 and the image on the imaging element 21 of the focusingestimating part 2 when the first focusing estimating part 2 creates thefirst focusing estimated value indicating that the image on the imagingelement 21 is focused on. The present invention is not, however, limitedto this. For instance, a defocus quantity detected when manufacturingthe camera to which the eleventh embodiment is applied and a defocusquantity predicted when designed, may be previously written to a ROM,etc.

Further, the eleventh embodiment has been described so far, whereinthere are provided the first focusing estimating part of the crestclimbing type and the second focusing estimating part of the imagedeviation type, the correction value is used for the focusing estimatingpart. The present invention is not, however, restricted to this. Theremay suffice the apparatus according to the present invention, whichcomprises the plurality of focusing estimating parts for creating thefocusing estimated values for focusing the image upon the object, whichimage is formed on the predetermined plane by the photographing opticalsystem, the storage device stored with the correction value for thefocusing estimated value created at least one of these focusingestimating parts, and the correcting portion for correcting the focusingestimated value with the correction value, which estimated valuecorresponds to the correction value stored in the storage device.

Moreover, the autofocus apparatus in the eleventh embodiment can beapplied to not only the video camera but also other cameras such as theelectronic still camera, etc.

A twelfth embodiment of the present invention will be hereinafterdiscussed with reference to the drawings.

FIG. 46 is a schematic block diagram illustrating an autofocus apparatusin the twelfth embodiment of the present invention. FIG. 47 is anexplanatory flowchart showing an operation of the autofocus apparatusillustrated in FIG. 46. FIG. 48 is an explanatory estimating partillustrated in FIG. 46. FIG. 49 is an explanatory flowchart showing anoperation of the second focusing estimating part shown in FIG. 46.

The autofocus apparatus in the twelfth embodiment includes, asillustrated in FIG. 46, the photographing optical system 1, the firstfocus estimating part 2, the second focusing estimating part 3, thefocusing method selecting device 4, the motor 5, the motor drivingdevice 6, and a position detecting device 17. Incidentally, if theautofocus apparatus in the twelfth embodiment is applied to the videocamera, etc., it is a general construction that the lens barrelincorporates the photographing optical system 1 and the motor 5, whilethe camera body incorporates other constructive elements. The presentinvention is not, however, limited to this construction.

The photographing optical system 1 is constructed of four lens unitssuch as the focus adjusting lens 11, the variable magnification lens 12,the correcting lens 13, and the image forming lens 14. This constructionis typical of the lens barrel for a TV camera. In the photographingoptical system 1 used in the twelfth embodiment, the optical element(e.g., the beam splitter) 45 for splitting light beams and the stop 16are interposed in between the correcting lens 13 and the image forminglens 14. Note that the optical the light beams can be transmitted to thesecond focusing estimating part 3 irrespective of an aperture quantityof an aperture stop of the photographing optical system 1 in the twelfthembodiment.

The position detecting device 17 detects an item of data for specifyinga position of the image forming lens 14.

The first focusing estimating part 2 estimates focusing by the so-calledcrest climbing method. The first focusing estimating part 2 includes theimaging element 21 for picking up an image formed by the image forminglens 14 of the photographing optical system 1 and converting it into anelectric signal, and the picture signal making device 22 for generatinga picture signal corresponding to the electric signal transmitted fromthe imaging element 21. The first focusing estimating part 2 alsoincludes the focusing estimated value creating device 23 for creatingthe data (the first focusing estimated value) for focusing the imageformed on the imaging element 21 on the basis of the picture signalgiven from the picture signal making device 22. The focusing estimatedvalue creating device 23 has the level detecting portion 23 a fordetecting a level of a proper frequency component from the picturesignal generated by the picture signal making device 22, and theestimated value creating value by examining the level detected by thelevel detecting portion 23 a. Note that the electric signal outputtedfrom the imaging element 21 is used also for generating the picturesignal of the video camera as illustrated in FIG. 46.

The second focusing estimating part 3 estimates focusing by theso-called image deviation method. The second focusing estimating part 3comprises the mirror 31 for reflecting the light beam split by theoptical element 45, toward a predetermined direction, and the imageforming lens 32 for forming light beams incident via the mirror 31 intoa conjugate image. The second focusing estimating part 3 furthercomprises the image re-forming lenses 33 a, 33 b for forming some of thelight beams image formed by the image forming lens 32, again intoimages, the line sensors 34 a, 34 b for respectively picking up theimages formed by the image re-forming lenses 33 a, 33 b and convertingthem into electric signals, the image processing device 35, and thefocusing estimates value creating device 36.

The image re-forming lenses 33 a, 33 b are disposed in positionssubstantially symmetric with respect to the optical axis of the imageforming lens 32. More specifically, the image reforming lenses 33 a, 33b are so disposed as to individually re-form the images of the lightbeams passing through portions having the focus adjusting lens 11, thevariable magnification lens 12, the correcting lens 13 and the imageforming lens 32, among the light beams for forming the image formed bythe image forming lens 32. The line sensors 34 a, 34 b are disposed inthe positions substantially symmetric with respect to the optical axisof the image forming lens 32 and on a predetermined focal surface of theimage re-forming lenses 33 a, 33 b corresponding to each other. Theimage processing device 35 executes the image processing based on theelectric signals transmitted respectively from the line sensors 34 a, 34b. The focusing estimated value creating device 36 creates the data (thesecond focusing estimated value) for focusing the image on the imagingelement 21 on the basis of the signal transmitted from the imageprocessing device 35. The focusing estimated value creating device 36includes the positional deviation detecting portion 36 a for detectingan imaging positional deviation (a deviating direction and a deviationquantity) between the image on the imaging element 34 a and the image onthe imaging element 34 b on the basis of the signal transmitted from theimage processing device 35, the correcting portion 36 b for correctingthe imaging positional deviation detected by the positional deviationdetecting portion 36 a, and the estimated value creating portion 36 bfor creating the positional deviation corrected by the correctingportion 36 b.

The correcting portion 36 b is stored with a table showing arelationship between the position of the image forming lens 14 and theimaging positional deviation detected by the positional deviationdetecting portion 36 a when focusing the image on the imaging element 21upon the object. The correcting portion 36 b obtains an imagingpositional deviation corresponding to the position data of the imageforming lens 14, which is detected by the position detecting device 7from that table, and corrects the imaging positional deviation detectedby the positional deviation detecting portion 36 a, with the thusobtained imaging position deviation serving as a correction value.

The focusing method selecting device 4 selects at least one of the firstfocusing estimated value created by the first focusing estimating part 2and the second focusing estimated value created by the second focusingestimating part 3. In accordance with the twelfth embodiment, referringfirst to the second focusing estimated value, if the defocus quantity orthe required-for-focusing moving quantity of the focus adjusting lens 11is larger than a threshold value, the second focusing estimated value isset to be selected, focusing estimated value is set to be selected. Notethat this threshold value may also be set arbitrarily by thephotographer and so forth through inputting from outside.

The motor driving device 6 drives the motor 5 on the basis of thefocusing estimated value selected by the focusing method selectingdevice 4. Based on a command given from the motor driving device 6, themotor 5 moves the focus adjusting lens 11 forward and backward in theoptical-axis direction of the photographing optical system 1.

Incidentally, the focusing estimated value creating devices 23, 36, andthe focusing method selecting device 4 are integrally constructed of,e.g., the CPU (Central Processing Unit), etc.

Next, an operation of the autofocus apparatus in the twelfth embodimentwill be described.

To start with, the operation of the autofocus apparatus as a whole inthe twelfth embodiment will be explained with reference to FIG. 47.

At first, upon an incidence of the light beams upon the photographingoptical system 1 from the object, the first focusing estimating part 2creates the first focusing estimated value on the basis of the lightbeams obtained via the image forming lens 14 in the photographingoptical system 1. Further, the focusing estimated value based on thelight beams split by the optical element 45 in the photographing opticalsystem 1 (step 271).

Next, the focusing method selecting device 4 judges whether or not thefirst focusing estimated value gives an indication of being focused(step 272). If the first focusing estimated value indicates a purport ofbeing focused, a flow of processing shown in FIG. 47 comes to an end.Whereas if not, the processing proceeds to step 273.

In step 273, the focusing method selecting device 4 refers to the secondfocusing estimated value, and judges whether or not the defocus quantityor the required-for-focusing moving quantity of the focus adjusting lens11 is under the threshold value. If the required-for-focusing movingquantity of the focus adjusting lens 11 is under the threshold value,the first focusing estimated value created by the first focusingestimating part 2 is selected (step 274). Whereas if above the thresholdvalue, the second focusing estimated value selected by the secondfocusing estimating part 3 is selected (step 275).

Next, the motor driving device 6 drives the motor on the basis of thefocusing estimated value selected by the focusing method selectingdevice 4 (step 276). When the second focusing estimated value isselected by driving device 6 drives the motor 5 so that the focusadjusting lens 11 is moved in the moving direction by the movingquantity, which are indicated by the selected second focusing estimatedvalue. Further, when the first focusing estimated value is selected bythe focusing method selecting device 4, it is estimated that the focusadjusting lens 11 is moving in such a direction as to approach afocusing point. At this time, the motor 5 is driven to make the rotatingdirection thereof remain unchanged. Moreover, when it is estimated thatthe focus adjusting lens 11 is moving in such a direction as to get awayfrom the focusing point, the motor 5 is driven to reverse the rotatingdirection thereof.

The processing flow shown in FIG. 47 is repeatedly executed till thefirst focusing estimated value comes to have a content of being focused.The image on the imaging element 21 is thereby focused on.

Subsequently, an operation of the first focusing estimating part 2 inthe twelfth embodiment will be explained with reference to FIG. 48.

At first, the picture signal making device 22 converts the image formedon the imaging element 21 through the photographing optical system 1into a picture signal (step 351). As described in the prior art, thepicture signal is, it can be assumed, formed frequencies. Then, it iswell known that a level of high frequency component of the picturesignal, as illustrated in FIG. 51, rises more sharply according as adegree of sharpness of the image formed on the imaging element 21increases, i.e., the focus adjusting lens 11 moves closer to a focusingpoint A, and this level reaches a peak when the image on the imagingelement 21 is focused on. Subsequently, the focusing estimated valuecreating device 23 causes a level detecting portion 23 a to detect aproper high frequency component level at a predetermined samplinginterval in consideration of an S/N ratio of the picture signal as wellas of an imaging performance of the photographing optical system 1, outof the picture signal of the picture signal making device 22 (step 352).Then, an estimated value creating portion 23 b creates the firstfocusing estimated value by monitoring a change in the detected level(step 353). For example, when the level of the selected frequencycomponent rises, it is estimated that the focus adjusting lens 11 ismoving in such a direction as to approach a focusing point. Further,when the level of the selected frequency component lowers, it isestimated that the focus adjusting lens 11 is moving in such a directionas to get away from the focusing point. Then, when the level of theselected frequency component exists within a from the peak value, it isestimated that the image on the imaging element 21 is focused on.

Note that the processing flow shown in FIG. 48 is repeatedly executed ata predetermined time interval taking a processing speed, etc. in thepicture signal creating device 22 into consideration.

Next, an operation of the second focusing estimating part 3 in thetwelfth embodiment will be explained with reference to FIG. 49.

To start with, the positional deviation detecting portion 36 a detects adeviating direction and a deviation quantity between the images pickedup by the line sensors 34 a, 34 b on the basis of the signalstransmitted from the image processing device 35 (step 451). As stated inthe prior art, when the light beams traveling through the image forminglens 32 are focused on the predetermined focal surface 37, some of thelight beams are again formed on the line sensors 34 a, 34 b by the imagere-forming lenses 33 a, 33 b. Hence, if focused on the predeterminedfocal surface 37, the images picked up by the two line sensors 33 a, 33b are formed in substantially coincident positions on the line sensors.On the other hand, when the light beams passing through the imageforming lens 32 are focused on anterior to the predetermined focalsurface 37 (which is the so-called rear focus state), there must linesensors 34 a, 34 b. Also, when the light beams passing through the imageforming lens 32 are focused on posterior to the predetermined focalsurface 37 (which is the so-called front focus state), there must be adeviation in a direction opposite to the one in the rear focus statebetween the images picked up by the two line sensors 34 a, 34 b. Basedon the deviating direction and deviation quantity between the imagespicked by the line sensors 34 a, 34 b, it can be therefore estimated howfar the image on the predetermined focal surface 37 exists away from thefocusing point.

Next, the correcting portion 36 b obtains the imaging positionaldeviation corresponding to the data about the position of the imageforming lens 14 which position is detected by the position detectingdevice from the stored table (step 452), and corrects the imagingpositional deviation detected by the positional deviation detectingportion 36 a, with the thus obtained imaging positional deviationserving as a correction value (step 453). Incidentally, the following isan elucidation of the reason why the imaging positional deviationdetected by the positional deviation detecting portion 36 a is correctedbased on the position data of the image forming lens 14.

If the predetermined focal surface 37 and the part 2 are coincident witheach other in terms of their optical positions, viz., if the image onthe imaging element 21 is focused on when the image on the predeterminedfocal surface 37 is focused on, there can be directly made an estimationas to whether or not the image on the imaging element 21 is focused onin accordance with the image deviating direction and quantity that aredetected by the positional deviation detecting portion 36 a. However, ifthe optical positions of the predetermined focal surface 37 and of theimaging element 21 deviate from each other, and if the predeterminedfocal surface 37 and the imaging element 21 deviate in terms of theiroptical positions due to, e.g., the tracking adjustment, the image onthe imaging element 21 is not focused on when the image on thepredetermined focal surface 37 is focused on. Therefore, the estimationas to whether or not the image on the imaging element 21 is focused onis made based on the image deviating direction and quantity that aredetected by the positional deviation detecting portion 36 a, thefocusing accuracy declines. Such being the case, in the twelfthembodiment, the correcting portion 36 b is stored with the tableindicating the relationship between the position of the image forminglens and the imaging positional deviation detected by the positionaldeviation detecting portion on the object. Detected from this table isthe imaging positional deviation corresponding to the data about theposition of the image forming lens 14, which position is detected by theposition detecting device 17. Then, the imaging positional deviationdetected by the positional deviation detecting portion 36 a iscorrected, with the thus detected imaging positional deviation servingas a correction value.

Next, the estimated value creating portion 36 c creates the secondfocusing estimated value indicating a moving direction and a movingquantity of the focus adjusting lens 11, which are needed for focusingthe image on the imaging element 21, on the basis of the positionaldeviating direction and quantity of the imaging positional deviationcorrected by the correcting portion 36 b (step 454).

Note that the processing flow shown in FIG. 49 is repeatedly executed ata predetermined time interval in consideration of the processing speed,etc. in the image processing device 35.

In the twelfth embodiment, the first focusing estimating part 2 createsthe first focusing estimated value by use of the so-called crestclimbing method, while the second focusing estimating part 3 creates thesecond focusing estimated value by employing the so-called imagedeviation method. Further, the focusing estimated value when the secondfocusing estimated value created by the second focusing estimating part3 is above the threshold value, and selects the first focusing estimatedvalue when under the threshold value. Then, the motor driving device 6,based on the focusing estimated value selected by the focusing methodselecting device 4, drives the motor 5 to move the focus adjusting lens11. With this operation, to begin with, the image on the imaging element21 is roughly focused on by use of the second focusing estimated value,and thereafter the image on the imaging element 21 is finely focused onby use of the first focusing estimated value. Accordingly, in accordancewith the twelfth embodiment, the image on the imaging element 21 can befocused on quickly with a high accuracy. Further, the high accuracy isnot required of the second focusing estimating part 3 using the imagedeviation method, and hence the costs can be restrained from rising.

Moreover, in the twelfth embodiment, the imaging positional deviationcorresponding to the data of the position of the image forming lens 14that is detected by the position detecting device 7, is detected fromthe table, with which the correcting portion 36 b is stored, showing therelationship between the position of the image forming lens 14 and theimaging positional detecting portion 36 a when the image on the imagingelement 21 is focused on the object. Then, with the detected imagingpositional deviation serving as the correction value, the imagingpositional deviation detected by the positional deviation detectingportion 36 a is corrected. Therefore, even if there might be caused thedeviation between the optical positions of the predetermined focalsurface 37 and of the imaging element 21 because of the image forminglens 14 being moved due to, e.g., the tracking adjustment with theresult that the image on the imaging element 21 is not focused on whenthe image on the predetermined focal surface 37 is focused on, thefocusing accuracy of the second focusing estimated value can beprevented from declining.

Note that the image on the imaging element 21 is focused on by use ofthe first focusing estimated value in the end in accordance with thetwelfth embodiment, and hence, even when the focusing accuracy of thesecond focusing estimated value declines, the final focusing accuracy ofthe image on the imaging element 21 does not change. If the focusingaccuracy of the second focusing estimated value declines, however, atime of focusing operation involving the use of the first focusingestimated value created by the first focusing estimating part 2elongates correspondingly. the imaging element 21 elongates. In thisrespect, according to the twelfth embodiment, as discussed above, thefocusing accuracy of the second focusing estimated value can beprevented from declining, and therefore, even if there might be causedthe deviation between the optical positions of the predetermined focalsurface 37 and the imaging element 21 due to the tracking adjustment,etc., the image on the imaging element 21 can be focused on quickly withthe high precision.

Furthermore, in the twelfth embodiment, a focal length of the opticalsystem for forming the images for detecting the image deviation on theline sensors 34 a, 34 b, is a synthetic focal length of the focusadjusting lens 11, the variable magnification lens 12, the correctinglens 13 and the image forming lens 32. On the other hand, a focal lengthof the optical system for forming the image for the picture signal onthe imaging element 21, is a synthetic focal length of the focusadjusting lens 11, the variable magnification lens 12, the correctinglens 13 and the image forming lens 14. Therefore, the focal lengths ofthe optical system for forming the images for detecting the imagedeviation and of the optical system for forming the image for thepicture signal, are varied by changing the configurations of the imageforming lenses 14, 32, respective optical systems can be varied. Forinstance, the image forming lens 32 is constructed to enlarge the imagesfor detecting the image deviation by increasing the focal length of theoptical system for forming the images for detecting the image deviation,whereby the pixel pitches of the lines sensors 34 a, 34 b become finerrelatively to the above images. Hence, it is feasible to focus even aminute object. Further, for example, the image forming lens 32 isconstructed to diminish the images for detecting the image deviation byshortening the focal length of the optical system for forming the imagesfor detecting the image deviation, whereby the sizes of these imagesbecome smaller relatively to the line sensors 34 a, 34 b. Therefore, itis possible to detect a larger quantity of image deviation. Even if thefocus adjusting lens is positioned far from the focusing point (which isthe so-called largely defocused state), the focusing point can bethereby quickly detected. Also, the apparatus can be downsized.

Next, a thirteenth embodiment of the present invention will behereinafter discussed with reference to the drawings.

FIG. 50 is a schematic block diagram illustrating the autofocusapparatus in the thirteenth embodiment of the present invention. Notethat the elements having shown in FIG. 46 are marked with the like orcorresponding numerals in the thirteenth embodiment of the presentinvention, and the detailed explanations thereof are omitted.

A different point of the autofocus apparatus in the thirteenthembodiment from the twelfth embodiment shown in FIG. 46, is that asecond focusing estimating part 3 a substitutes for the second focusingestimating part 3, and there are provided a motor 18 and a motor drivingdevice 19.

The second focusing estimating part 3 a is different from the secondfocusing estimating part 3 shown in FIG. 46 in terms of such a pointthat an image forming lens 32 a for forming the light beams incident viathe mirror 31 and emerging from the object into a conjugate image, is sodisposed as to be movable in the optical-axis direction and that thefocusing estimated value creating device 38 does not include thecorrecting portion 36 b. The focusing estimated value creating device 38makes the estimated value creating portion 36 c create the secondfocusing estimated value based on the deviating direction and thedeviation quantity of the imaging positional deviation detected by thepositional deviation detecting portion 36 a.

The motor driving device 19 is stored with a table showing arelationship between the position of the forming lens 32 a, from whichthe image on the imaging element 21 and the image on the predeterminedfocal surface 37 become conjugate to each other. The motor drivingdevice 19 obtains the position of the image forming lens 32 a whichcorresponds to data about the position of the position of the imageforming lens 14, which position is detected by the position detectingdevice 17 from that table, and drives the motor 18 so that the imageforming lens 32 a comes to this obtained position. Incidentally, if aformula well expresses the relationship between the position of theimage forming lens 14 and the position of the image forming lens 32 a,from which the images on the imaging element 21 and the image on thepredetermined focal surface 37 become conjugate to each other, theposition of the image forming lens 32 a that corresponds to the data ofthe position of the image forming lens 14 which position is detected bythe position detecting device 17, may be obtained by use of this formulainstead of using the above table.

Based on a command from the motor driving device 19, the motor 18 movesthe image forming lens 32 a in the optical-axis direction thereof.

In the thirteenth embodiment, the position of the image forming lens 32a that corresponds to the data of the position of the image forming lens14 which 17, is detected from the table stored in the motor drivingdevice 19 and showing the relationship between the position of the imageforming lens and the position of the image forming lens 32 a, from whichthe image on the imaging element 21 and the image on the predeterminedfocal surface 37 become conjugated to each other. Then, the imageforming lens 32 a is moved so that the image forming lens 32 a comes tothe detected position concerned. Therefore, even when the image forminglens 14 moves due to, e.g., the tracking adjustment, it is possible toprevent the deviation in the optical positions between the predeterminedfocal surface 37 and the imaging element 21. This further makes itfeasible to prevent the focusing accuracy of the second focusingestimated value from declining. Other effects are the same as those inthe twelfth embodiment of the present invention.

The present invention is not confined to the respective embodimentsdiscussed above by may be modified in a variety of forms within thescope of the gist thereof. For example, in each of the embodiments givenabove, the apparatus has been described so far, wherein the crestclimbing type first focusing estimating part and the image deviationtype second focusing estimating part, are provided, and the focusingestimated value created by the second focusing not, however, limited tothis. The apparatus according to the present invention may comprise theplurality of focusing estimating parts for creating the focusingestimated values for focusing, on the object, the image formed on thepredetermined plane through the photographing optical system. Theapparatus may also comprise the position detecting portion for detectingthe position data of the image forming lens in the photographing opticalsystem, and the position detecting portion for detecting the positiondata of the image forming lens in the photographing optical system. Theapparatus may further comprise the correcting portion for correcting thefocusing data created by at least one of the focusing estimating partson the basis of the data about the position of the image forming lens,which position is detected by the position detecting portion.

Moreover, the autofocus apparatus in the embodiments discussed above isapplicable to not only the video camera but also other cameras such asan electronic still camera and so on.

As discussed above, in the autofocus apparatus according to the presentinvention, the first focusing estimating device creates the focusingestimated value, involving the use of the so-called crest climbingmethod. The second focusing estimating device creates so-called imagedeviation method. Then, the focusing estimation selecting device selectsat least one of the focusing estimated values created by the first andsecond focusing estimating devices, and the focus adjusting lens ismoved based on the thus selected focusing estimated value.

Hence, according to the autofocus apparatus of the present invention, tobegin with, the image on the first imaging element is roughly focused onby use of the focusing estimated value of the second focusing estimatingdevice, and thereafter the image on the first imaging element is finelyfocused on by use of the focusing estimated value of the first focusingestimating device. It is therefore feasible to perform the focusingquickly with the high accuracy.

Further, according to the autofocus apparatus of the present invention,if one of the first and second focusing estimated values is useless, thefocusing on the object can be surely performed by selecting the otherestimated value.

Moreover, according to the autofocus apparatus of the present invention,at least one of the first and second focusing estimated values isselected referring to the depth of field. With this operation, if thefocusing accuracy in the first focusing estimating device is inferior tothe focusing accuracy in the estimation selecting device can be set toselect the data from the second focusing estimating device. The focusingcan be thereby effected quickly with the high precision.

Also, when the autofocus apparatus of the present invention is providedwith the above-constructed object dimension calculating device, theobject dimension setting device and the focusing object controllingdevice, it is possible to focus on only a specified object (e.g., humanbeing) from within the photographic area by focusing on the relevantobject only when, for instance, the object real dimension calculated bythe object dimension calculating device is coincident with the dimensionof the photographing target, which dimension is set by the objectdimension setting device.

Additionally, when the autofocus apparatus of the present invention isprovided with the above-constructed focus area setting device, forexample, the focus area of the first focusing estimating device is setsmaller than the focus area of the second focusing estimating device. Adetection sensitivity of the imaging positional deviation in the secondfocusing estimating device can be thereby decreased. This enables aresolution of the second imaging element to increase, and therefore thecost for the second

Further, in other autofocus apparatuses of the present invention, withthe constructions given above, for instance, only when the object realdimension calculated by the object dimension calculating device iscoincident with the photographing target dimension set by the objectdimension setting device, the focusing on the object concerned iscarried out. Thus, it is feasible to focus on only the specified object(e.g., human being) from within the photographic area.

Furthermore, the camera according to the present invention has the aboveconstruction and therefore exhibits the same effects as those in theautofocus apparatus of the present invention.

According to the lens barrel of the present invention, with theconstruction described above, the image on the imaging element can befocused on by employing the two types, i.e., the crest climbing type andthe image deviation type of the autofocus systems. Owing to thisconstruction, at first, the image on the imaging element is roughlyfocused on by using the image deviation method, and, thereafter, theimage on the imaging element is finely focused on by using the crestclimbing method. The image on the imaging element can be thereby focusedon quickly with the high accuracy. Further, since the camera bodyincorporates the first focusing estimating part usable in common opticalsystem, the lens barrel can be prevented from rising in costs and can bedownsized.

Moreover, according to the lens barrel of the present invention, thelens barrel incorporates the two types, viz., the crest climbing typeand the image deviation type of the autofocus mechanisms, whereby theimage on the imaging element can be focused on quickly with the highprecision even if the camera body is constructed not corresponding tothe autofocusing.

According to the camera of the present invention, owing to theconstruction given above, if the camera body does not include the firstfocusing estimating device, the autofocus function can be actualized byemploying the second focusing estimating device of the lens barrel.Further, if the camera body has the first focusing estimating device,the autofocus function can be actualized by using the second focusingestimating device of the lens barrel as well as using the first focusingestimating device of the camera body.

According to the lens barrel of the present invention, the lens barrelincorporates the crest climbing type autofocus mechanism, therebyenabling the image on the imaging element to be focused on highlyaccurately even though the camera body is constructed not correspondingto the autofocus.

According to the lens barrel of the present deviation type autofocusmechanism, whereby the image on the imaging element can be focused onquickly even if the camera body is constructed not corresponding to theautofocus.

Moreover, according to the present invention, for example, there areprovided the crest climbing type and image-deviation type focusingestimating devices. To start with, the image on the predetermined planeis roughly focused on by use of the focusing data of the image deviationtype focusing estimating device. Thereafter, the selecting device is setso that the image on the predetermined plane is finely focused on bymaking use of the focusing data of the crest climbing type focusingestimating device. Thus the focusing can be done quickly with the highaccuracy.

Moreover, as one of the plurality of focusing estimating devices, thelight beams diverge from the photographing optical system for formingthe image on the imaging surface of the camera body as in the imagedeviation type focusing estimating device, and the image is formed in adifferent position from the above imaging surface, thus estimatingwhether or not the image on the imaging surface is focused on by use ofthe relevant image. Even when using this estimating system, the storagedevice stores, as the correction value, the deviation in the opticalpositional body and the surface formed with the image for focusingestimation, and the focusing data of the corresponding focusingestimating device is corrected by using the thus stored correctionvalue, thereby making it feasible to prevent the decline in the focusingaccuracy when employing the relevant focusing estimating device.

Further, as one of the plurality of focusing estimating devices, thelight beams diverge from the photographing optical system for formingthe image on the imaging surface of the camera body as in the imagedeviation type focusing estimating device, and the image is formed in adifferent position from the above imaging surface, thus estimatingwhether or not the image on the imaging surface is focused on by use ofthe relevant image. Even when using this estimating system, the positiondata of the image forming lens is detected, and there is obtained thedeviation in the optical positional relationship between the imagingsurface of the camera body and the surface formed with the image forfocusing estimation. Then, the focusing data of the correspondingfocusing estimating device is corrected with the thus obtained deviationserving as the correction value, thereby making it possible to preventthe decline in the focusing accuracy when using the relevant focusingestimating device.

range of different working modes can be formed based on the inventionwithout deviating from the spirit and scope of the invention. Thisinvention is not restricted by its specific working modes except beinglimited by the appended claims.

1. An autofocus apparatus comprising: a photographing optical systemhaving at least a focus adjusting lens disposed movably and an imageforming lens to form, into an image, light beams incident on said focusadjusting lens and emerging from an object; a plurality of focusingestimating devices to create focusing data to focus an image formed on apredetermined plane through said photographing optical system, upon theobject; a storage device stored with a correction value for the focusingdata created by at least one of said plurality of focusing estimatingdevices, said correction value being stored differently from thefocusing data; an updating device to update the correction value storedin said storage device at a predetermined timing; a correcting device tocorrect, with the correction value, the focusing data corresponding tothe correction value stored in said storage device; a selecting deviceto select at least one of said plurality of focusing estimating devices;and a moving device to move said focus adjusting lens on the basis ofthe focusing data created by said focusing estimating device selected bysaid selecting device, or the relevant corrected focusing data if therelevant corrected focusing data has been corrected by said correctingdevice.
 2. An autofocus apparatus according to claim 1, wherein saidpredetermined timing in said updating device is a timing incorrespondence with operation by the user for updating.
 3. An autofocusapparatus according to claim 1, wherein said predetermined timing insaid updating device is a timing in correspondence with trackingadjustment.
 4. An autofocus apparatus comprising: a photographingoptical system having at least a focus adjusting lens disposed movablyand an image forming lens to form, into an image, light beams incidenton said focus adjusting lens and emerging from an object; a focusingestimating device to create focusing data to focus an image formed on apredetermined plane through said photographing optical system, upon theobject; a storage device stored with a correction value for the focusingdata created by said focusing estimating device, said correction valuebeing stored differently from the focusing data; an updating device toupdate the correction value stored in said storage device at apredetermined timing; a correcting device to correct, with thecorrection value, the focusing data corresponding to the correctionvalue stored in said storage device; and a moving device to move saidfocus adjusting lens on the basis of the focusing data created by saidfocusing estimating device, or the relevant corrected focusing data ifthe relevant corrected focusing data has been corrected by saidcorrecting device.
 5. An autofocus apparatus according to claim 4,wherein said predetermined timing in said updating device is a timing incorrespondence with operation by the user for updating.